Series / Kamen Rider Zi-O

Spoilers for all Heisei Kamen Rider entries preceding this one, including Kamen Rider Build, will be left unmarked. You Have Been Warned!

Go beyond space-time!

The legacy of the Heisei Kamen Riders has carried on throughout the era.
And now, they pass their power on to the new generation!
Rejoice! For the birth of a new king!

— Opening Narration (By Rikiya Koyama, Episodes 1-16)

Kamen Rider Zi-O (仮面ライダージオウ) is the 2018-2019 entry in the Kamen Rider series, the twentieth and final entry in the franchise's Heisei era, and the twenty-ninth entry overall. It aired alongside Kaitou Sentai Lupinranger VS Keisatsu Sentai Patranger in the Super Hero Time block, followed by Four Week Continuous Super Sentai Strongest Battle, and later, Kishiryu Sentai Ryusoulger. It ended on August 25, 2019, and was succeeded by Kamen Rider Zero-One, the first series of the Reiwa era.

In the year 2068, fifty years into the future, the world is ruled by an Evil Overlord named Ōma Zi-O: a Kamen Rider who seized the powers of every Heisei Kamen Rider who came before him to become the "Overlord of Time" on the Day of Ōma. The only option left for the dwindling La Résistance is to send two of their members back in time to Set Right What Once Went Wrong by assassinating Ōma Zi-O before he can achieve his full power.

Arriving into the year 2018, they locate the younger version of Ōma Zi-O as described in their history books: an ordinary and naive eighteen-year old named Sougo Tokiwa who childishly dreams of becoming "a king" that can bring happiness to the world. One of the Resistance members (Geiz Myokoin, aka Kamen Rider Geiz) is insistent on completing the assassination, but the other (Tsukuyomi) begins to question if the pure-hearted Sougo is really capable of growing up into the tyrannical Ōma Zi-O.

As Sougo claims the power of Kamen Rider Zi-O and embarks on the road to ascension, the history of the Kamen Riders begins to distort as various parties aim to twist the future to their advantage. A mysterious group of time-travelers named the Time Jackers begin to steal the power of the Kamen Riders, creating their own Another Riders as candidates to usurp Ōma Zi-O as the Overlord of Time. A sycophantic "prophet" of Ōma Zi-O named Woz arrives from the future to ensure the ascension of his master as history dictates. And standing beside Sougo are Tsukuyomi and Geiz, carefully watching his actions with a hand on their weapons. Will Sougo create an unexpected destiny as "the most beloved and kind Overlord in history", or is he fated to become the ultimate evil?

Kamen Rider Zi-O's tie-in projects include:

• Kamen Rider Zi-O: Supplementary Plans, a web video series on Toei's fan club site where characters break the Fourth Wall to discuss information that supplements the story and setting of the first 16 episodes. The episodes are included among the normal episode counts (designated "Episode [x].5").
• Kamen Rider Heisei Generations FOREVER, the annual crossover movie teaming Zi-O with Kamen Rider Build.
• A set of Rider Time bonus episodes exclusive to Toei's Toku Fan Club that feature some of the returning and original Riders that Zi-O encounters.
  • Rider Time: Kamen Rider Shinobi, showing viewers a small glimpse into the hypothetical adventures of Shinobi.
  • Rider Time: Kamen Rider Ryuki, written by veteran writer Toshiki Inoue, detailing Sougo and Geiz aiding Shinji Kido and Ren Akiyama in stopping a new Rider War.
  • Rider Time: Kamen Rider Decade vs. Zi-O: Decade's Death Game and Rider Time: Kamen Rider Zi-O vs. Decade: Seven Zi-Os, set after the series and released simultaneously. While Decade and Diend were major supporting characters during the show's final arc, these are full-fledged crossovers between the two series. This also serves as the Grand Finale for both shows.
• Kamen Rider Zi-O: Over Quartzer, the summer movie.
• Kamen Rider Bibibi no Bibill Geiz, a Televi Kun Magazine magazine exclusive DVD episode.
• Kamen Rider Reiwa: The First Generation, the next crossover following the Heisei Generations films. This one bridges the Heisei and Reiwa eras by pairing Zi-O with his successor Kamen Rider Zero-One.
• Kamen Rider Zi-O NEXT TIME: Geiz, Majesty, a direct-to-video movie set after the end of the series. (While it was implied that more NEXT TIME specials were in the works, none were ever announced.)
• Novel: Kamen Rider Zi-O, an interquel between the Series Finale and Geiz, Majesty. It has the main characters battling forces from an Alternate Universe where the events of the main story are stopped by force, with a certain Alternate Self of Sougo taking over.

Not to be confused with its predecessor Kamen Rider ZO (which is actually pronounced "Zet-Oh" as per the Japanese pronunciation of the letter Z, while this one is "zi-oh") or its distant relative Power Rangers Zeo.

For the Showa-era equivalents, see Birth of the 10th! Kamen Riders All Together!! and its manga adaptation, Kamen Rider Spirits. For the Super Sentai equivalent, see Kaizoku Sentai Gokaiger.

---

Recurring Kamen Rider tropes include:

• Actor Allusion:
  • Or rather, Suit-Actor Allusion, for Geiz's suit actor Yuya Nawata. In the OOO Arc, Geiz gets the Genm Armor, which is based off Kamen Rider Genm, Nawata's first in-suit role as a Kamen Rider.
  • Rikiya Koyama as the Evil Counterpart of The Hero from another timeline? Sounds familiar.
• Cool Bike: Both Zi-O and Geiz have the Ride Striker, which transforms from a stopwatch into a motorcycle.
• Defeat Equals Explosion: Played straight for the Another Riders.
• Early-Bird Cameo: The franchise traditionally has a new Rider cameo in the previous Rider's summer movie, and Zi-O gets hit with this on both ends:
  • Zi-O first appeared in Kamen Rider Build: Be The One, when Build briefly crossed dimensions. The Cross-Z Ridewatch also appears in Build's finale, but Zi-O itself appears to ignore and Retcon this bit.
  • Zi-O's own movie, Over-Quartzer, has his successor Kamen Rider Zero-One appear.
• Henshin Hero: All over the place.
• Monster of the Week: Another Riders, humans who use the power of prior Riders with Another Watches, but are twisted into monstrous forms.
• Merchandise-Driven: As always, the show revolves around collectible little trinkets. The collectibles this time are called Ridewatches, pocket watches with the faces of previous Kamen Riders. Or in Woz's case, future Kamen Riders.
• Previously on…: Each episode begins with Woz giving a brief recap of the previous episode, ending with some brief foreshadowing of the events of the current episode, framed as Woz reading the events from his book.
• Sixth Ranger: Kamen Rider Woz, Woz's Rider form from an alternate future.
• Spell My Name With An S: Zi-O is a particularly bad season for finicky spellings, with Punny Names all over the place:
  • Geiz's name, pronounced "Geitsu", was logically assumed to be "Gates," until the Ziku-Driver's LED text display revealed the spelling to be Geiz.
  • Every "ji" sound is officially romanized as "z": Zi-O, the Ziku-Driver, the Time Mazine, the various Zikan weapons, etc.
  • The Time Jackers suffered from this a lot, but none worse than poor Heure, whose name is a French word that sounds odd being spoken by Japanese speakers. Previously fans thought his name was "Uhr" or even "Wool". Similarly, Ora's name was thought to be spelled "Hora" or "Aura". We only received confirmation on both when the TV Asahi website added bios for their custom Time Mazines. And we never did get any information on whether the third member is "Sworz", "Swortz", "Schwartz", or something else.
  • Kamen Rider WozGingaFinaly is spelt with just one "l" instead of the usual two in the word "finally", but is still pronounced the same.
  • The movie Riders in Over Quartzer are particularly bad, as their names are katakana anagrams of the shows they're based off of, with no regard to how they'd work in English. "Amazons" translates cleanly to "Zamonas", while "Shin/ZO/J" only has the issue of where to stick the H, resulting in things like "Zhonjis", "Zonjhis", or "Zonjish" (or "Zonjis", if you're willing to drop it); but there is no good way to anagram "Black RX" into a seven-letter word with only one vowel. You'll see that one written as "Barx", "Burks", "BRX", "Barlux" or "Balrux", etc.; or even "Barlckx" if the writer is committed to keeping the anagram. A magazine eventually confirmed the official spellings as Zamonas, Zonjis (no H), and Barlckxs (full anagram with an S for some reason).
• Transformation Trinket:
  • The Zikū-Driver (Spacetime-Driver), used by both Zi-O and Geiz as well as Tsukuyomi/Alpina, is the main transformation device, while forms are changed with Ridewatches (similar to Decade's Rider Cards). Similar to the Drivers in Ex-Aid, it has two slots for Watches, with one used for the personal transformation and the second for power-ups.
    • The Oma Zi-O Driver, an evolved form of the Zikū-Driver, used by Oma Zi-O. Unlike its predecessor, it does not have slots for Watches, as none are needed for transformation.
  • Woz uses the BeyonDriver and Miridewatches ("Future Ridewatches").
  • All three receive unique Watches for upgrade forms. The Zi-O Ridewatch II splits into two and is slotted into both sides of the Zikū-Driver, while the Geiz Revive Watch is an hourglass that grants two modes depending on which side is up. The Zi-O Trinity Watch flips open to cover the Ziku Driver's main display. The Ginga Miridewatch is larger and can rotate for different forms.
• Super Mode: All three Riders get one: Zi-O has Grand Zi-O, Geiz has Geiz Revive, and Woz has Woz Ginga.
• Weapon Specialization:
  • The Zikan Girade is Zi-O's weapon. It can transform between a sword (Ken) and a gun (Jū). As Zi-O II, he gets a second sword called the Saikyō Girade; and the latter can attach to the former to form a BFS, the Saikyō Zikan Girade.
  • The Zikan Zax belongs to Geiz. It has bow (Yumi) and ax (Ono) modes. In his Revive forms, he instead uses the Zikan Jaclaw, a circular saw (Nokogiri)/claw (Tsume) weapon.
  • The Zikan Despear is used by Woz. It's a staff whose head can switch between spear (Yari), sickle (Kama), and cane (Tsue) modes.
  • Most Rider Armors also feature their own weaponry:
    • The Build Armor has the Drill Crusher Crusher, a drill mounted as a Blade Below the Shoulder.
    • The Ex-Aid Armor has the Gashacon Breaker Breakers, dual Power Fists. Notably, though, the Genm Armor doesn't despite being otherwise identical; it draws more from Genm's Shakiriki Sports upgrade than the Mighty Action X base powers.
    • The Drive Armor has the Shift Speed Speeds, two car drones that the user can launch.
    • The Fourze Armor has the Booster Module rocket arms.
    • The Faiz Armor has the Faiz Shot Shots, knuckle weapons.
    • The OOO Armor has a set of Tora Claw Z Wolverine Claws.
    • The Gaim Armor is Multi-Armed and Dangerous with four Daidaimaru Z swords.
    • The Decade Armor has the Ride HeiSaber ("Heisei Saber"), a Cool Sword that can channel other Riders' powers without even using Ridewatches.

I think... I can list these tropes!

• Aborted Arc:
  • Invoked and played for drama beginning around the halfway point of the series, as the ongoing Time Crash causes several of the pre-established rules regarding Another Riders to cease to apply. The Day of Oma itself undergoes multiple changes regarding when it's scheduled and what it's supposed to mean, some of which are the product of characters lying about its nature^note The Dai Mazines are really under the control of SOUGO and have nothing to do with Oma Zi-O as Black Woz initially claims, while White Woz was deliberately misleading Geiz about the real purpose of Geiz Revive while others are a result of space-time getting tangled into knots.
  • Geiz Revive being a Deadly Upgrade. Producer Shirakura had even lampshaded this as Geiz himself attaining a power-up physically and likened it to getting used to a routine exercise.
  • During his brief tenure on the show, Minato alludes to there being a true form of Zi-O that's been corrupted into the one we see, but provides no details beyond that the true Zi-O doesn't have a form that looks like Grand Zi-O.
• Actor Allusion:
  • Kamen Rider Shinobi/Kagura Rentaro was previously StarNinjer, and if that's not enough, his Rider belt has a spinning shuriken and the soundbyte "DARE JA?! ORE JA!! NIN-JAAAA!!" Taken a step further in Rider Time: Kamen Rider Shinobi, where one of Rentaro's opponents in the ninja tournament wears a gold costume and cowboy hat.
  • Kamen Rider Kikai is a walking reference to Jingi Irie's previous role in Kikaider REBOOT; Kikai's ice powers, on the other hand, reference his role as Zamigo Delma in Kaitou Sentai Lupinranger VS Keisatsu Sentai Patranger.
  • Another Decade's head resembles the helmet of Jinga's Horror form in the GARO franchise, a nod to Masahiro Inoue's other big Tokusatsu role.
• All There in the Manual: The Saikyō Girade's name is never actually spoken in the show as it doesn't announce itself like the other weapons in the show, and is only known through supplementary material.
• Alternate Timeline:
  • The Geiz Revive timeline is this to the originally linear Oma Zi-O timeline.
  • #37 hints and #38 outright states that Kamen Rider Kabuto happened in an alternative timeline and currently the Kabuto timeline and the Zi-O timeline are mixing for some reason, causing time-space distortions.
    • Tsukasa reveals in #48 that just like his premise, all Kamen Riders originate from different timelines/Worlds. However due to Swartz turning Sougo into a Doom Magnet, Sougo subconsciously pulls their timelines into his in order to meet them to obtain their powers. Eventually as Sougo has obtained all of them, all the Kamen Riders' timelines have effectively merged into a single world, allowing Swartz to execute the final stages of his Master Plan to destroy the combined world.
  • #43 reveals that Swartz and Tsukuyomi are from a different timeline than the show. Swartz arriving here for his plan while Tsukuyomi was sent to a different timeline in an attempt to kill her by Swartz and just so happened to arrived in this timeline.
• Ambiguous Ending: Woz notes at the end of the show that it's possible the new timeline that Sougo has created will somehow lead him to become Zi-O — or even Oma Zi-O — again. Whatever happens, though, it won't be the future that had been written in Woz's book. Disambiguated with the Kamen Rider Zi-O NEXT TIME movie, Geiz, Majesty. They all get their Rider powers again, plus a few new ones.
• Artifact Title: Taken to an even further extent than the previous Rider series. While there the motorcycles were known to be underused, there was at least a few instances where they were featured. In Zi-O however, Sougo rides the bike so little that the total amount of footage of him on it only amounts to 47 seconds.
• Attack of the 50-Foot Whatever: Another Kuuga is much larger than the regular riders, being of a size equivalent to the mecha forms of the Time Mazines.
• Bad Future: Preventing one where Zi-O takes over the world and rules as an Evil Overlord is the entire plot.
• Badass Boast: The toy-exclusive Decade Complete Ridewatch boldly announces "Saikyo wa ore da~!" when activated by the Ziku Driver, roughly translating to "I'm the strongest around!" While simple, it's the only potential form out of hundreds that does this (including the other 19 final form watches), and is entirely justified since the hypothetical DecadeCompleteArmor is, after all, tapping into the All Your Powers Combined form of the previous anniversary Rider for maximum carnage.
• Bigger on the Inside: The Time Mazine's cockpit is about twice as large as external shots imply, given that it has enough space for multiple people besides the pilot to just walk around freely.
• Breather Episode: In some ways, the Hibiki tribute is this: While there's still the dilemma regarding Another Hibiki and gaining the Hibiki Ridewatch, the two episodes also deal with Sougo's 19th birthday with Woz (hilariously) struggling how to celebrate his day. The tribute ends on a rather happy note regarding Kyosuke retaking Tsutomu as his apprentice and Sougo getting celebrated by his close ones, coming right between the Agito tribute that dealt with Tsukuyomi having time powers and the Kiva tribute that deals with Kamen Rider Ginga and ending in Sougo experiencing love pain.
• Brought to You by the Letter "S": All Riders have "Kamen Rider" written on their faceplates; "Kamen" (カメン) is the shared Rider logo this season, it appearing on everybody's armor in various places and the visors are "Rider" in katakana (ライダー) for most Riders and in hiragana (らいだー) for Geiz. When using a Rider Armor, the "Kamen" forehead inscription is dropped, while the visors change to that Rider's name.
  • If you look close enough at Ōma Zi-O's faceplate,◊ it has the kanji for "king" (王) repeatedly imprinted on the blank space.
  • At the Back of the Ziku Driver, you can see it says "べ ル ト" ^note "Belt".
  • The underside of the wrist-mounted Ridewatch Holder has "holder" written in katakana as well.
  • Some Rider Armors inherit letter logos from their original Rider as well (like Decade's X, Double's W, or Drive's K/R). The OOO Armor adds a new one, with its TaToBa chestplate redesigned with the names of OOO's theme animals タカ^note Taka, "Hawk", トラ^note Tora, "Tiger" and バッタ^note Batta, "Grasshopper" in place of the original's images of those animals. The Double Armor also has giant Gaia Memories for shoulderpads, which like the original Memories are labeled C and J for Cyclone and Joker.
  • The Decade Armor has even more name labels: The original Rider's name moves from the visor to the shoulder, and the chestplate and other shoulder show the name of that Rider's upgrade; so that taken together they read things like "Build Sparkling" and "Ghost Grateful". The faceplate also mimics Decade's cards and has the Rider's name in English in the lower corner. In base version of the armor, the place where the upgrade name would be instead shows a generic barcode with the numbers 2009 (Decade's airing year) and 453145 ("DECADE" in alphanumeric).
  • Grand Zi-O's shoulder and chest armor are shaped such that the silver parts from shoulder to chest form the shape of "ZIO" in English.
  • Another Riders have this in the form of their Rider names and the year they originate from displayed in English on their bodies.
  • Supplementary Plans #15.5 continues the gag in an imaginary trailer for "Kamen Rider Tsukuyomi"; while we don't see her actual Rider suit, the Ridewatch shows that her visor uses English letters but can only fit part of the name ("TSUKU") on the helmet. In #48, we finally get to see Kamen Rider Tsukoyomi; her helmet has the word "Rider" in katakana like everyone else.
• Canon Foreigner: Where Zi-O and Geiz receive armors based on past Riders, Kamen Rider Woz's form changes are based on "future" Riders that don't exist "yet": Kamen Riders Shinobi, Quiz, and Kikai. Ginga was similarly created for Zi-O while being completely unconnected to the show's plot or design theme.
• Casting Gag: The future Kamen Riders are played by Super Sentai alumni^note The odd man out here is Kamen Rider Ginga, who's never shown untransformed (and might not even have a human form). He's played by voice actor Tomokazu Sugita, who has played roles for both Sentai and Kamen Rider, most prominently Kivat-Bat the 3rd.:
  • Kamen Rider Shinobi is played by Hideya Tawada, Shuriken Sentai Ninninger's Kinji Takigawa/Starninger
  • Kamen Rider Quiz is played by Katsuhiro Suzuki, Tokumei Sentai Go-Busters' Hiromu Sakurada/Red Buster.
  • Kamen Rider Kikai is played by Jingi Irie, Kaitou Sentai Lupinranger VS Keisatsu Sentai Patranger's Zamigo Delma; he also starred in 2013's Kikaider Reboot movie (which crossed over with Kamen Rider Gaim), so Kikai has references to both roles.
• Catch-22 Dilemma: Swartz's plan with Another Shinobi boils down to this. As previously established, the heroes need the Shinobi Ridewatch to beat Another Shinobi; however, they have to beat Another Shinobi to obtain the Ridewatch in the first place. They can't get it the normal way because Shinobi exists in a parallel timeline and they're unable to cross over. Sougo finds another way by convincing Rentaro to believe in his future self and "break" his contract with the Time Jackers, which allows White Woz to create the Ridewatch using his tablet.
• Cerebus Call-Back: Woz delivers one final "Rejoice!" speech in the last episode, but it's not as funny as the others because he's "rejoicing" to the fact that Sougo, driven past the Despair Event Horizon by his friend Geiz's death, finally accepted his fate and became Ohma Zi-O. Woz is initially speechless, but a bitter, broken Sougo outright orders him to start rejoicing.
• Chekhov's Boomerang: In the first part of the show, Sougo has to give blank Ridewatches to Legend Riders in the past so that they absorb part of the Riders' power and transform into Legend Ridewatches by the time Sougo needs them. This concept was dropped as the story progressed, being Handwaved as a result of changes to the timeline. It comes back in a big way in the final arc: Sougo travels to 2068, specifically arriving during the events of #1, just before Ohma Zi-O curb-stomps the Resistance and inspires Geiz and Tsukuyomi to go back in time in the first place. He secretly slips a Blank Watch into Tsukuyomi's pocket, and by the time he returns to 2019 for the final battle with Swartz, it's transformed into a Ridewatch that lets Tsukuyomi become a Kamen Rider in her own right.
• Chekhov's Gun: Tsukasa's contingency plan to restore his powers from his Ridewatch after Swartz stole his powers becomes significantly more important when it was shown that the same plan was later used for Tsukuyomi in light of Swartz also stealing her powers, allowing her to restore her own powers with the additional benefit of turning her into a Kamen Rider.
• Clingy Macguffin:
  • The Ridewatch that becomes the Zi-O Ridewatch keeps finding its way to Sougo until he decides to become Zi-O.
  • Justified with the Ziku-Driver itself. In #16, Geiz destroys Sougo's Driver (at his request), but Woz anticipated that this might happen and created a "backup" Driver.
• Continuity Nod: As an anniversary series, this series is chock full of them.
  • At the first episode, Sougo meets Sento Kiryu (Takumi Katsuragi) and Ryuga Banjo in the cafe nascita... but as Build's history is wiped because the creation of Another Build, they become fans of Taro Satou (a.k.a. the man with Sento's modified face) instead.
  • In 2018, Emu Hojo and Hiiro Kagami are still doctors on Seito University Hospital. Emu is a pediatrician while Hiiro apparently managed to become the director.
  • Takumi Inui still works with the Kikuchi Dry Cleaners laundry service.
  • Chuta Ohsugi is still a teacher at Amanogawa High School. Meanwhile, Gentaro Kisaragi is also a teacher who initiated the Kamen Rider Club during high school and eventually became its advisor, but is out investigating the missing female students case. Nezu and Kong, two of Sanagiman's Smug Super thugs in Kamen Rider × Kamen Rider Wizard & Fourze: Movie War Ultimatum, return as actual students of Amanogawa High, but due to timeline changes their descent to villainy never happened, making them genuinely good schoolboys that have never met any Riders before Sougo and Geiz.
  • Kuroto Dan still works under his father Masamune in Genm Corp, suffering writer's block due to stress from living up to him that ended up being his motive for killing him.
  • Eiji Hino became a Japan diet member to reach his helping hand out to everyone he can.
  • Kouta Kazuraba is still a space god when the timeline is correct otherwise he's still working at Drupers in the modified timeline. The dance troupe Team Baron also continues to exist.
  • Takeru Tenkuji is still living at Daitenku Temple, investigating supernatural phenomena with his friends Shibuya and Narita.
  • Tsukasa Kadoya is still dimension hopping as Decade, with Daiki Kaito chasing after him. He's there to destroy the World of Zi-O should it become too unstable.
  • Ryotaro Nogami is still active as Kamen Rider Den-O and is currently working as part of the Den-Liner Police, continuing from the Climax Deka movie. Later on in the show, Yuto is still traveling across time with his Imagin partner Deneb.
  • At #21, it is revealed that ORE Journal from Kamen Rider Ryuki is closed because of social media's influence.
  • The cafe Jacaranda from Kamen Rider Blade is still thriving, with Amane Kurihara as its owner. Kazuma Kenzaki and Hajime Aikawa are still avoiding each other as Jokers.
  • At the ending of Kamen Rider Agito, Shouichi Tsugami opened his own restaurant. In Zi-O, he travels to France to learn about cooking, leaving Mana Kazaya as the owner. Takahiro Omuro is a captain in the police force now, leading the resurrected G3 unit.
  • The ancient organization of "Oni" in Kamen Rider Hibiki still exists, with Kyosuke Kiriya and Todoroki as active members. It seems that Makamous are still roaming the land too.
  • Jiro is still following his vow to aid the heir of Castle Doran. He still drinks at Café mald'amour, now renamed Aroma and brings up his unrequited crush on Yuri Aso.
  • This becomes deconstructed once Arata Kagami appears, commenting on the destruction of Shibuya which has the heroes realize that time is being distorted somehow since not even Woz has information on an event such as that. ZECT is also brought up and are still around and Yaguruma is still in his nihilistic state of mind and mourning his partner Kageyama.
• Darker and Edgier: Even more so that it's spiritual predeccessor. This series opens with a very brutal Bad Future of Oma Zi-O crushing the Resistance forces and decimating them all, with Geiz and Tsukuyomi trying to guide Sougo away from being the most vile demon king. As the show progressed, Sougo has more of his Friendless Background emphasized with a few episodes of Geiz and Tsukuyomi staying distant from him in favor of White Woz's side, the fact that Sougo and Hiryu lost their parents in a bus crash that Swartz orchestrated, the Kiva tribute being much more dramatic and intense than previous tributes before it, and the Another Zi-O II three-parter has Sougo suffering from a timeline change caused by Hiryu where nearly almost everyone he knows is against him. Then there's also the fact that the show's final act deals with time paradoxes that lead to monsters from all over the Heisei era with the risk of breaking reality and unlike previous final battles, the climax of Sougo's involves him becoming Oma Zi-O over grief of Geiz dying to save him and then tearfully and infuriately finishing Swartz after the latter also kills Tsukuyomi.
• Department of Redundancy Department:
  • The Rider Armors' weapons, such as Build Armor's Drill Crusher Crusher and Ex-Aid Armor's Gashacon Breaker Breakers.
  • Maoh Oma Zi-O can be interpreted as Demon King King Demon Time King. Sougo actually complains about how cheap his future self's naming sense has become.
  • Exclusive to the toyline, the Build Genius Ridewatch sings out "Chou Tensai! Build Genius!" when slotted into the Ziku Driver. Translated literally, this roughly equates to "the super genius, Build Genius."
• Diabolus ex Nihilo: Kamen Rider Ginga is an Omnicidal Maniac from space who crash lands on Earth riding on a meteoroid and immediately goes on a destructive rampage. He's presumably from the future, as he has the same kitbash suit design style and belt as Shinobi, Quiz, and Kikai, and he serves no purpose in the story besides being a temporary obstacle and getting Woz his Final Form, Woz Ginga. Ultimately, he's just a symptom that the laws of time are starting to break down, and in the next arc the characters briefly wonder if the Worms coming to Earth on meteors has any relation.
• Double-Meaning Title: The obvious translation of "Zi-O" is "Time King", but "zi" is also a homophone for the word for "written character". Therefore, Zi-O is also the "Character King" and has an extreme case of Brought to You by the Letter "S" and Exactly What It Says on the Tin. Also, just like with Kamen Rider ZO, the Z and O in the name visually look like the number 20 for a 20th anniversary series.
• Early-Installment Weirdness: The opening two-parter of the show differs from all those that follow in a few major ways regarding the premise:
  • The changes to Sento and Ryuga's personalities are drastic and played primarily for comedy. All future returning Riders remain heroic figures even without their powers, and are mostly the same in terms of personality (with the notable exception of Kusaka, who is less of an ass in this timeline.)
  • Another Build is presented as barely sentient and possessed by a demented take on Build's personality that forces him to attack people at random. All future Another Riders are in control of themselves and use their powers for personal gain, with their existing personalities and goals already playing off the themes of the Rider whose powers they've stolen. This is later justified when it's explained that Another Riders are feral if the power was forced on them, while the ones who knew exactly what they were getting into and chose the power are able to use it and stay themselves.
  • The creation rules of Another Riders are different in the first half of the show. In it, the creation of Another Riders in the past are instantly wiping the overall history of the corresponding riders (Build, Ex-Aid, Faiz, Fourze, Gaim, and Ghost). In the second half, as Another Riders are created in the present (2019), the corresponding riders' power and history are left intact and the past Riders get to transform and fight much more often than they did in the early phase of the season as well.
• Evil Knockoff: The Another Riders: monstrous versions of the Heisei Riders themselves.
• Exactly What It Says on the Tin: A common design theme for this series, not only do the Riders' main forms read "Kamen Rider" in Japanese on their faces, Zi-O's eyes changes to the name of the Kamen Rider whose powers he has equipped as his armour.
  • This extends to their weapons as well, Zi-O's Zikan Girade reads ケン^note ken and ジュウ^note jū for sword and gun modes respectively. Geiz's Zikan Zax has おの^note ono, announced as "Oh! No!" and ゆみ^note yumi, announced as "You! Me!" for ax and bow modes respectively.
  • Ride Striker has バイク^note baiku, as in "bike" on the wheels. It comes from the Bike Ridewatch which itself has the katakana on it rather than the usual Kamen Rider face.
  • Zi-O's Time Mazine mecha has a large ロボ^note robo plastered on its torso. Geiz's is labeled ろぼ, the same in hiragana. Seemingly lampshaded in #1, where Sougo incredulously says "'Robo'?" when Geiz's Time Mazine appears in front of him.
  • Although not easily seen on the show (except in Kuuga, which used a Zorro Mark), magazine scans show that most Riders' boots have custom designs on the soles. Zi-O's and Geiz's soles are labeled with "kick" in either Katakana^note キック or Hiragana^note きっく as appropriate.
  • This also gets played with when Zi-O uses Build's powers; Due to Sougo himself being bad at math, Build's usual floating equations are replaced with sentences saying "Hard to understand equations", "Some numbers here" and the like.
  • The Riders' gear also has labels incorporated into their designs in out-of-the-way places; the back of the Zikū-Driver is labeled ベルト^note beruto, i.e. belt and the Ridewatch Holder has ホルダー^note horudā, as in holder on its underside.
  • Even the Another Riders are labeled, with their respective Riders' names in English stamped somewhere on their bodies.
• Exty Years from Publication: The future characters' home time, 2068, is exactly fifty years from the present day.
• Fighter, Mage, Thief: The three main Riders: Geiz is the fighter, Woz is the thief, and Zi-O is the mage.
• Foreshadowing:
  • The Evolving Credits give zero indication of who is in the Kamen Rider Woz suit, unlike Zi-O and Geiz. It's the only one that changes hands eventually.
  • The opening always shows Tsukuyomi with the Time Jackers, it's revealed that by the half way of the show that she has powers similar to them.
  • The opening also has shots of the Heisei Rider statues from the "Sougo Tokiwa's First Transformation" monument crumbling, revealing the actual Riders beneath the stone. These exact shots ended up appearing in the series proper as part of Grand Zi-O's transformation sequence.
  • In Heisei Generations Forever when Tsukuyomi loses her memories, she doesn't know why someone would call her Tsukuyomi. This hints that her real name isn't actually Tsukuyomi, it's Alpina.
  • Swartz's statement to Woz that he and Tsukuyomi are cut from the same cloth is revealed he was being literal; they're siblings as shown in #38.
  • Tsukuyomi being from another timeline is hinted when she and Tsukasa visit her past in #38 and they see her childhood home is a huge house in 2058. Tsukuyomi said the remaining people still alive under Oma Zi-O's rule, live in refugee camps which makes it odd that Tsukuyomi's family alone is living in luxury.
  • After the DenLiner crashes, forcing the Taros to interact with the heroes in #39, Ora wonders why is it that Zi-O seems to draw in the various Kamen Riders. #48 reveals that Sougo is an actual Doom Magnet set up by Swartz to pull in the various Riders and their timelines.
  • Every single one of Woz's rejoice speeches start by saying Sougo is the heir to the powers of all Riders. The last episode reveals Woz wasn't embellishing, Oma Zi-O has the powers of every Rider that ever existed.
• For Want Of A Nail: As a result of the actions of the main characters, many events that were originally foretold to happen, happened differently, but special mention goes to the Day of Oma which in turn changed completely as a result of several events:
  • The appearance of White Woz.
  • Zi-O II and Geiz Revive both appearing earlier than foretold.
  • Sougo unable to get six of the 20 Ridewatches.
  • The creation of the Trinity Ridewatch which gave birth to Zi-O Trinity instead of Oma Zi-O appearing.
• From Bad to Worse: The final arc is pretty much a series of the heroes managing to resolve one horrible event only for an even worse situation to rear its head before they can even catch a break. First, Sougo gets Ret-Gone, and Hiryu returns, more powerful than before, and becomes an even worse Oma Zi-O. Then, it's revealed that the whole thing was bait to lure Tsukasa into a trap so that Swartz can steal his powers to become Another Decade, who promptly starts using his powers to abduct innocents to fuel an army of Dark Riders. Then the slow-burning Time Crash that's been going on throughout the show hits full stride, causing an outbreak of monsters from all across Heisei Kamen Rider History, and threatening to break reality unless something is done about it. And Tsukasa is thinking that "something" is destroying the world to protect the rest of The Multiverse from the potential fallout.
• Fully Absorbed Finale: While the series is one for the Heisei era of Kamen Riders as a whole, several Heisei Rider series that had initially ended on notes ranging from Downer to Bittersweet like Kamen Rider Blade get far better closure here.
• Future Badass:
  • Oma Zi-O, the evil Demon King ruling the Bad Future, who is far stronger than his present self. Showcased heavily when it comes to the actual fight between him and his present self, which is a complete Curbstomp Battle.
  • Time alterations create an alternate future where Geiz becomes the savior, Geiz Revive, and kills Oma Zi-O. White Woz hails from this timeline.
• Gambit Pileup: By the series midpoint Zi-O is essentially the story of a bunch of different time travelers playing chess against each other to alter the future to their ideal outcome.
  • Tsukuyomi helps Sougo collect the Ridewatches, in the hopes of swaying him so he won't become the Demon King. Geiz has a similar goal, but with less tact and more extreme methods.
  • The Time Jackers want to supplant Ohma Zi-O with one of their Another Riders and use him as a Puppet King to rule through.
  • "Black" Woz serves Ohma Zi-O in the current future and wants to make sure Sougo's journey stays the same, while his alternate "White" Woz comes from a different timeline that emerged due to changes to the past and assists Geiz, guiding him so he'll defeat Zi-O and his future will be the one that comes to be.
  • Ohma Zi-O himself sent Woz back in time to ensure his rise to power still comes to be, and later sends Kasshin to eliminate Geiz.
  • There's also two players in the pileup who have hidden ulterior motives. The Time Jacker Swartz is secretly manipulating Sougo to become King so he can harness his power for his own ends, and Black Woz is actually a member of the Quartzer, an order which seeks to use Sougo to unify all the Rider timelines so they rewrite the history of the Heisei Kamen Riders.
• Gotta Catch 'Em All:
  • Collecting the three Miridewatches was required to produce the Geiz Revive Ridewatch.
  • While collecting the Legend Ridewatches was seemingly dropped due to Sougo gaining greater powers that rendered their use obsolete, #30 reveals that his ongoing ascension to Oma Zi-O still required him to collect all 20 Ridewatches aside from Zi-O II's power, foreshadowing tribute arcs for the last six Ridewatches to obtain. And they mean it, as when Sougo does get all 20, he finds that the Drive Watch doesn't count since Geiz stole it from Oma Zi-O before the series began; Sougo needs to get his own.
• Grand Finale: Zi-O serves as the final entry of Kamen Rider's Heisei era, which started with Kamen Rider Kuuga way back in 2000.
• Gratuitous Spanish/Italian: Geiz Majesty's finisher is "El Salvatore Time Burst", combining the Spanish and Italian for "The Saviour".
• Greater-Scope Villain:
  • Ōma Zi-O. He's the reason the conflict even exists, but, for most of the series, isn't actually involved. The danger lies more in becoming him than opposing him. Subverted when it's revealed that Oma's reign was due to Swartz's manipulations in the first place. Swartz is just the Big Bad with no Greater Villain above him.
  • Then it's revealed in Over Quartzer that no, the Sougo of the true original timeline (Kamen Rider Barlckxs) was behind Swartz seeking out a King in the first place, and ensured that it would be Sougo's younger self. Barlckxs wants to destroy the current Heisei generation and replace it with on where he becomes Oma Zi-O, with all of Zi-O's powers plus the Heisei Showa Riders.^note That is, the Riders that are considered Showa but actually debuted during the Heisei period, which he and the other members of Quartzer already have.
• His Name Is...: White Woz falls victim to this in episode 46 as he's about to relay what Swartz's true plan is.
• Hitler's Time Travel Exemption Act: This idea is essentially one of the main tropes of the series, with Sougo as the Hitler. Tsukuyomi and Geiz come back in time to kill him, but are waffling on whether or not to go through with it. The situation is complicated by other parties that have also come back in time, either to preserve Oma Zi-O's reign or manipulate it to their own benefit.
• Homage: With the exception of Kuuga (who gets its sole tribute in the Winter Movie), each of the past shows has some kind of tribute within the storyline of the TV show whether through a character or the episode arc's story following similarly to the past show. Some are shared such as the following:
  • Faiz and Fourze having an arc together.
  • Kiva sharing its tribute with the Ginga story.
  • W and Drive combining their tributes with the Movie Rider arc and the last episodes respectively.
  • Decade continuing his story throughout the series from the Ghost arc all the way to the end.
• Idiosyncratic Episode Naming: Each episode title of the first half of the series involves a short phrase related to the Rider it's giving tribute to, followed by one of the years the episode takes place in (usually the tributed Rider's year of origin). The latter half reverses this, putting the year first.
• In Spite of a Nail: Not unlike in previous time-travel series Kamen Rider Den-O, time travel works this way for good and ill. Making lasting changes to history is difficult: even with the Ridewatches outright ripping Riders out of existence, backstory and all, they and their friends still gravitate together despite no longer having any reason to have met. On the flipside, it means it'll take a lot more than Sougo simply resolving not to become the tyrant Oma Zi-O in order to make it so.
  • #4.5 emphasizes this by pointing out that non-Rider Hiiro Kagami is almost identical. Some of the other Riders are changed more though, such as Kaixa being alive.
• La Résistance: There is a large resistance force in 2068 fighting against the tyranny of Ōma Zi-O. Sadly, they're pretty much fighting a losing battle, thanks to Ōma Zi-O being the Physical God that he is. Both Tsukuyomi and Geiz are members.
• Leaning on the Fourth Wall: When Zi-O first uses Ex-Aid's Critical Time Break finisher, a cut-in and text effects appears onscreen in the style of the original Critical Strike, only for Zi-O to instead knock away the special effects and use the text as projectiles instead. (Also, since Sougo is not a genius like Sento, instead of equations the text says things like "some numbers here" instead of the complex equations, and Sento is able to actually see them and comment that it isn't quite right...)
• Legion of Doom: The last few episodes sees the Rider worlds all being converged into one and the heroes having to fight a massive horde of past Rider enemies. The final episode has Sougo having a showdown with five past Kamen Rider Big Bads and Final Bosses.
• Loophole Abuse: Apparently the rules of time travel here mean that Another Riders are replacing the canon Riders in the timeline, causing the Rider forms to dissipate even if the characters are left alive, just unpowered. But Power Copying is a part of Zi-O's skill set, so copying said disappeared Riders is still fair game.
• Make Wrong What Once Went Right: The Time Jackers apparently want Zi-O to take over — just with their own candidate in the role.
• Mangled Catch Phrase: Sougo sometimes repeats previous Riders' catchphrases, but since he barely knows anything about them, he always gets those phrases wrong.
• Meet Your Early-Installment Weirdness: Beautifully inverted in the Kamen Rider Blade arc - Kenzaki and Hajime actually witnessed malevolent Sharing a Body firsthand with Mutsuki and the Spider Undead, but then it was Played for Laughs during Kamen Rider Den-O and Kamen Rider W, and by the time of Zi-O it's become a Recurring Element.
• Mêlée à Trois: Zi-O vs the Time Jackers vs Woz, all of which are trying to alter history in some way or another (or in Woz' case, not alter history) that are mutually exclusive. On the occasion where he's in 'kill Zi-O' mode, Geiz may also fight independently and against Zi-O.
• Mini-Mecha: The Time Mazines, which can change into a motorcycle-like vehicle mode and travel through time. Tsukuyomi and Geiz have their own personalized versions, the former of which becomes Zi-O's machine, and they can use Ridewatches to gain the powers of the Kamen Riders just like their users. The Time Jackers also have Time Mazines, which they enhance with other Rider gear: Heure uses Ghost's Captain Ghost and Ora has Kiva's Castle Doran.
• Mythology Gag: Has its own page.
• Never the Selves Shall Meet: Averted; there's never been an issue with meeting one's future or past self.
  • In the Gaim arc, Sougo initially defeated Another Gaim by himself, but Overlord Kouta intervened and encouraged him to trust his friends to gain their own strength. So, Sougo went back in time three days to try and change how he did things, only to eventually get discovered. Despite both Tsukuyomi and Woz railing at him about time paradoxes, nothing bad happens and the two Sougos get along swimmingly.
  • Also averted in #15, where Sougo comes face-to-face with himself in 2068, confirming that Ōma Zi-O really is him.
  • #38 has Tsukuyomi meeting her child self due to Tsukasa taking them back to 2058.
• Newspaper Dating: In #1, Sougo checks the expiration date on a milk carton Banjou is drinking from to confirm that he's really gone back to 2017.
• Only One Me Allowed Right Now: Only one of any specific Kamen Rider is allowed to exist at any given time. This means that when an Another Rider is created, the original Rider loses their powers and their memories of being a Rider. However, copying the powers of other Riders is fair game, and Zi-O and Geiz in fact have to use copied powers to take out the Another Riders for good. At one point during the Ghost arc, there's a battle with three "Ghosts": Another Ghost, Decade Ghost Form, and Zi-O Ghost Armor. Averted with Kamen Riders Den-O, Quiz, and Zi-O himself; as they were able to fight their Another counterparts just fine. According to Word of God, time paradoxes created after Zi-O and Geiz received upgrades mean this rule no longer applies after the series' halfway point; first seen in the Blade episodes.
• Painting the Medium: Rare In-Universe example when Sougo's lack of familiarity with all the past Riders leads to their attacks, catch phrases and even the SFX for some finishing moves coming out a little... off.
• Pietà Plagiarism: In #22, Tsukuyomi holds Geiz in this pose after he kills himself with a Time Burst against Another Ryuga. White Woz shouting "My savior!" drives it home double.
• Power Copying: Zi-O and Geiz can borrow the powers of previous Riders. Several other Riders could do this in spin-off media, but this is the first time since Decade that it's been featured in the main show. In fact, the Decade Watch lets Zi-O copy Decade's copying ability — it adds a third watch slot to enhance the Decade Armor with yet another Rider's powers.
  • Zi-O has an additional form of Variant Power Copying where attacks involving words and texts are stylized to fit Sougo more.^note e.g., Build's equations become vague lines akin to "Some numbers here", Ex-Aid's English "Hit" and "Critical" effects have been rendered in katakana ("ヒット" and "クリティカル").
  • The Another Riders also do this, but considering what they look like, there's clearly something wrong with the process.
• Punny Name:
  • Time Mazine. It's "Time Machine" with a "Z", but also puns on "majin", which means "devil".
  • The Jikan Gilade's name is a combination of the phrase "jikan girei" (which roughly means "time's up"), "giri" (slash), and the English word "blade". Similarly, the Zikan Zaxe and Zikan Zaclaw come from "jikan", "zakkuri" ("roughly") and "axe"/"claw".
  • Woz's Zikan Despear puns off of "spear" and the phrase "jikan desu" (literally "it's time", along the lines of "the time has come"), and each form change announcement puns off of the form's name; Spear Mode's phrase is "Yarisugi!", punning off of "yari" (spear) and "yarisugi" (too much, overkill), Sickle Mode's being "Kamashisugi!", punning off of "kama" (scythe) and "kamashisugi" (overpushing), and Cane Mode's being "Tsuesugi", punning off of "tsue" (cane) and "tsuesugi" (overwhelming).
• Red Herring:
  • In #5, Woz tells Sougo that the Another Fourze incident started with "a shooting star". After meeting the Kamen Rider Club, Sougo assumes Ryūsei Sakuta was involved, as his given name means "shooting star", only to find out Another Faiz/Fourze and the girl he's trying to save were orphans in the Ryūsei School.
  • In #9, Another OOO/Kuroto Dan drops a Genm Ridewatch which Geiz and Tsukuyomi picked up. Assuming his cracked origin year display read "2016", the same year indicated on the Ridewatch, they travel to 2016 to defeat him using Genm's powers. This ended in a failed attempt where Tsukuyomi realizes Another OOO's year display actually reads 2010, which meant that the Genm Ridewatch they obtained was not what they needed.
• Repetitive Name: So far every weapon provided by a Rider Armor takes its name from the item it's based on and doubling the last word. Examples include the Drill Crusher Crusher, the Shift Speed Speeds, and the Gashacon Breaker Breakers.
• Ret-Gone: The creation of an Another Rider causes the events of the Rider's original season to have never happened, and it seems like those events are still gone even after the Another Rider is destroyed (possibly due to the creation of the corresponding Ridewatch(es)). This rule is discarded halfway through the series, with Word of God blaming time paradoxes.
  • In the series finale arc, the very loose connected canon that the various Rider series are happening in the same universe is explicitly undermined. It's always had a lot of holes in terms of continuity and crossover with only 3 series (Drive, Ex-Aid and Build) going to exceptional lengths to tie every piece of media into the main continuity of each series. Mid-way through the series, a hint is dropped where Kagami is confused none of the Zi-O cast knows about the Worms. In Zi-O's finale there are multiple references to the Kamen Riders each occupying their own timeline. Tsukasa eventually spells it out: Each of the Kamen Riders exist on their own parallel time axis but following his trip to Build's past, each of Sougo's battles combined parts of that riders world with his. With the defeat of Another Drive and the rise of Another Decade, the world's are fully combined into one, with elements like the Skywall, Yggdrasil and Futo Tower appearing in Sougo's world. This is also a world Tsukasa has decided needs to be destroyed. End of an era indeed.
• Robot Buddy: Zi-O gets watch versions of some previous Rider robots, the Taka Watchdroid from OOO and Kodama Suika Arms from Gaim.
• Royalty Super Power: Swartz and Tsukuyomi come from a royal family whose bloodline gives them the power to control time.
• Running Gag: For some reason Zi-O seems to get his major upgrades during tribute arcs for card-based Riders:
  • Decade Arc - Decade Armor
  • Ryuki Arc - Zi-O II
  • Blade Arc - Zi-O Trinity
  • Den-O Arc^note While not exactly card-based, the Rider Tickets from the show have been promoted as collectible trading cards. - Grand Zi-O
• San Dimas Time: The Faiz Phone X even allows people in the past and present to make phone calls.
• Set Right What Once Went Wrong:
  • In order to prevent a Bad Future ruled by a "Demon King", Tsukuyomi goes back in time 50 years, finds the King back when he was an Ordinary High-School Student, and tries to stop him from becoming a villain. Geiz also wants to stop the Bad Future, but would rather take the more direct approach and kill Sougo before he becomes the demon king. He's convinced to instead spare him for now to see whether he really does become evil.
  • White Woz, at least on the surface, seems to be trying to do this: he wants to cause Geiz to become the savior Geiz Revive and avert the Bad Future by defeating Oma Zi-O.
• Shadow Archetype: The Ryuki arc focused on the return of Dark Shinji and the introduction of Dark Sougo. But instead of being the opposites of the real riders like in the original Ryuki, the mirror counterparts are more the darker impulses and fears of the riders that they hide instead. Dark Shinji is essentially Shinji's deep-seated anger at Ore Journal's readers abandoning them, causing the company to be closed; while Dark Sougo is Sougo's fear of becoming Oma Zi-O and how evil he truly is.
• Shoe Phone: As expected when drawing from 555, the heroes each have a Faiz Phone X that can switch between being a watch, a cell phone, and a blaster. The Faiz Armor itself also retains a few of these that were used by the original Faiz.
• Shoulders of Doom: Most of the Rider Armors have giant shoulderpads. Most of them are in the shape of the original Riders' Transformation Trinket or another Iconic Item associated with them. Thanks to being made of a trio of Transforming Mecha, the OOO Armor's shoulderpads are in the form of an actual tiger.
• Shout-Out:
  • When the cast asks Woz why Geiz's name is based on "gates" and not "gate" in #2.5, he tries to make the excuse that it makes Geiz sound rich, like a millionaire; referring to the tech mogul Bill Gates. This is also why Geiz's new form from the Hyper Battle DVD is officially transliterated as Bibill Geiz, which is lampshaded immediately afterward.
  Sougo: "Bi-Bill Gates?" *chuckles*
  • How do Sougo and the group enter the game world with the Genmboy? By entering the Konami Code.
  • The Faiz Phone X's name is read as "Faiz Phone Ten", much like the recently-released iPhone X.
  • #6.5 openly names Bleach as the reason why neither Fourze or Meteor returned for guest appearances.
  • In #11, Swartz thought Geiz was made of sterner stuff.
  • The arrival of White Woz involves wind and sparks of electricity around his point of arrival in the night.
  • In #16, Heure carefully picks up a yellow bell pepper before taking a bite with a grin. He even does the overdramatic flourish as he does it.
  • White Woz can write down the names of people along with the foreseen event that will affect them brings to mind the Death Note's users manipulating the cause and time of their victim's deaths.
  • Kamen Rider Shinobi can summon a mechanical toad that briefly stands upright, not only a nod to God Gammer but also the way it forms part of Kakure Daishogun.
  • #20's title is "Final Answer?".
  • Kamen Rider Quiz is pretty much a heroic take on the Riddler of Batman fame, and even the Zikan Despear in cane mode has its hook facing up to resemble a question mark.
  • The Bad Future that Kamen Rider Kikai comes from - humans have been hunted to near extinction, the only thing keeping them alive being a massive walled compound. And the Humanoise can still find a way in by passing for human. Good thing they don't grow to fifty feet tall...
  • Kamen Rider Tsukuyomi's transformation jingle sounds very similar to the first opening theme of Sailor Moon.
  • Tsukuyomi makes several to Ringu and Ju On in Bibill Geiz.
  • A good chunk of the basis of Kamen Rider: Bibibi no Bibill Geiz comes from Corpse Party or possibly Ghost Stories.^*Ghost Stories was considered infamously subpar by anime standards, and the American Gag Dub came as a result of it being forced into a package deal to make some kind of money off of it. The Gag Dub proved much more popular, even with the original creators.
• Spectacular Spinning: The Zikū-Driver works by inserting a Ridewatch and then spinning the Driver in a full circle.
• Spiritual Anti Thesis: To Kamen Rider Den-O, being a season about Time Travel and using that to defeat the Monster of the Week in the past. However, while Den-O's time travel was used to fix damages caused to the past and time, Zi-O's time travel and various other time alterations caused time to be damaged till it was pretty much hell on Earth with 19 years history of enemies the Kamen Riders faced which nearly forced Decade to destroy the world.
• Spiritual Successor: To Kamen Rider Decade, being a Milestone Celebration season celebrating the Heisei era reaching a multiple of ten years and focusing on borrowing previous Riders' powers. Zi-O also has magenta in his default suit design, which was Decade's main color. It also opens with a Flash Forward to the hero as an unstoppable villain in the future, and has the hero pursued by someone who wants to take him out because a certain crisis we know little about is supposedly all his fault. Decade himself even shows up as an important recurring character, and his Ridewatch acts as a Mid-Season Upgrade for Zi-O. Gradually, the continued presence of Decade and Diend morph Zi-O into a Stealth Sequel.
• Stable Time Loop: The entire show takes place within an extremely complicated one that involves multiple alternate timelines looping back on each other. Even the outright Time Crash parts are ultimately shown to be part of the loop. This plays into how Sougo is supposed to be ultimately convinced to become Oma Zi-O: the only way all of the alternate timelines, and his friends from them, can continue to coexist is for the loop to continue.
• Stealth Pun: The Ridewatches each have a picture of the Rider whose power they unlock. In other words, a watch face.
• Stealth Sequel: Of Kamen Rider Decade, due to Tsukasa and Daiki getting more involved in the story than the other past Heisei Riders.
• Story Arc: Their are four arcs in the show.
  • "Rider Time, the Demon King of Future", which pays tribute to Build, Ex-Aid, Fourze, Faiz, OOO, Wizard, Gaim, Ghost, and Decade, from Episodes 1 to 16.
  • "Trinity Time, Servant and Demon King and Saviour", which pays tribute to Ryuki and Blade, while dealing with the three future riders, Shinobi, Quiz, and Kikai, from Episodes 17 to 30.
  • "Grand Time, the New Future", which pays tribute to Agito, Hibiki, Kiva, Kabuto, and Den-O from Episodes 31 to 40.
  • "End Time, the Destruction and Reborn of the World", the final arc, which pays tribute to W, the Movie Riders, and Drive, while bringing closure to Decade and Diend's story from Episodes 41 to 49.
• Stringy-Haired Ghost Girl: Tsukuyomi intentionally users her hair to achieve this look in the Bibill Geiz Hyper Battle DVD movie.
• Surprisingly Realistic Outcome:
  • While Sougo dreams of being king, no one other than Geiz and Tsukuyomi takes him seriously, usually telling him to pursue something more grounded in reality.
  • After the rise of social media, the ORE Journal was rendered obsolete and ended up going out of business.
  • Hayase (Another Wizard) doesn't end up with Kaori just because he came clean with her about his feelings and everything. (Granted that happened in Kamen Rider Kiva, but not here...)
• Symbol Motif Clothing:
  • The Riders' armor is based on wristwatches, with the watch faces used as the helmet faces and the straps going down the front and over the head. Zi-O's is like a Rolex watch◊, Geiz' is a digital G-Shock watch◊, and Woz has a smartwatch. Geiz Revive also takes the timepiece theme in a different direction, being based on an hourglass.
  • In addition, Geiz's visor is vaguely butterfly-shaped. This is said to be a reference to the Butterfly Effect.
• Takes One to Kill One: One of the rules presented in #2.5 (to the audience) and #4 (to the characters) is that "An Another Rider can only be defeated by the same Rider's powers". However, since the Another Riders' existence negates the powers of the original Riders, this pretty much means that only Zi-O or Geiz can do the job once they get the appropriate Legend Rider Ridewatch. Eventually, this rule gets broken as our heroes' upgrades can simply overpower the Another Riders without needing to match the powersets.
• Team Mercy vs. Team Murder: Tsukuyomi believes that she can influence The Hero Sougo from becoming Oma Zi-O by influencing him and steering him away from his path peacefully, while Geiz believes killing him before he becomes the Evil Overlord is the way to prevent the Bad Future they both came from.
• Temporal Paradox:
  • The existence of Zi-O in the first place is one: Woz comes back in time and prophecies Zi-O's rise while Geiz is coming back to kill him and the Time Jackers are coming back to replace him with their own candidate. All three of these actors are directly responsible for Zi-O becoming Zi-O in the first place, despite all three of their motivations coming from his future self. Also, Woz is the one to give Zi-O the Ziku Driver in the first place, meaning Zi-O can only exist via the intervention of a servant of his future self. This is officially confirmed when its revealed that the reason behind the entire show's events and Sougo becoming Zi-O was due to the meddling of Swartz. His second Driver is Geiz's, which was also stolen from Oma Zi-O.
  • The Geiz Revive timeline is a similar paradox: Geiz comes back in time to stop the rise of Oma Zi-O, and succeeds by becoming Geiz Revive, defeating Oma Zi-O on the Day of Oma...a form he can only achieve by channeling the existence of Riders who only exist due to him beating Oma Zi-O given to him by a fanatical follower of his future self, and Geiz himself is from a Bad Future resulting from Oma Zi-O conquering the world.
  • The later half of the show starts to see reality break down in the face of so many paradoxes. Another Riders start co-existing with the actual Kamen Riders, alternate timelines start merging into Zi-O's timeline, and at one point Sougo is Ret-Gone, causing Hiryu to become an even worse Oma Zi-O. While the heroes intially don't seem to care too much about the cause at first, other parties show up to try and get rid of the source. Michal blames Tsukuyomi and Geiz for trying to change the past (in addition to the former being from another timeline entirely), while Tsukasa theorizes that Sougo is the source and that he might have to destroy the World of Zi-O before the distortions get out of hand.
• Terminator Twosome: Taken up to a threesome in this case:
  • Tsukuyomi and Geiz are the first team - they are both here to Set Right What Once Went Wrong, but she wants to push Zi-O away from villainy non-lethally, while he wants to kill him.
  • Woz is loyal to Ōma Zi-O, and the only one who wants to preserve history.
  • The third faction is the Time Jackers, out to change the timeline to Make Even More Wrong What Once Went Wrong.
  • And then later White Woz comes back from a different possible future where Geiz became Geiz Revive and defeated Oma Zi-O and as loyal to him as his prime self is to Zi-O. This makes him and Woz a unique case where two sides of this trope are the same person.
• The Story That Never Was: The show ends with Sougo, now possessing the unlimited powers of Oma Zi-O, using them to rewrite time so that none of the events of the show ever happened, with Geiz, Tsukuyomi, and the Time Jackers now Sougo's friends and classmates while the other Rider timelines are restored to their proper states. Only Woz retains his memories of the old timeline, while the show's ending was immediately followed by a trailer for Geiz's V-Cinema showing that at least some of the rest of the cast will eventually regain theirs.
• Time Crash: The second half of the show is essentially a slow-moving example, as the paradoxes created by all the various time travelers begin building up to the point of causing damage to the fabric of time itself. This leads to breakdowns of the pre-existing rules, multiple inconsistent timelines coexisting, and even events happening completely out of order. And yet even this is part of the Stable Time Loop that Swartz created. In #47, we see the full result as the various Rider histories are fusing with Sougo's world such as various structures from their histories like the Skywall, Fuuto Tower and Yggdrasill Tower appearing. This also results in the various monsters from those histories being summoned and terrorizing the public.
• Time Travel: Zi-O is from the present time, but Tsukuyomi, Geiz, Woz, and the Time Jackers are from the future (year 2068).
• Time Traveler's Dinosaur: When Tsukuyomi takes Sougo on a time-traveling trip via Time Mazine in the first episode, they end up at one point in the Cretaceous where they get chased by a Tyrannosaurus rex. Notably, most other examples of time travel within the show are only to times and places within the 21st century, so this instance stands out in comparison.
• Timey-Wimey Ball: Played With. The rules of time travel are established early on, and are generally consistent, even taking into account previous Kamen Rider series (like Den-O not disappearing due to being a Singularity Point, even after his Another Rider counterpart is made). However, all the alterations that everyone is trying to make to the timeline starts building up paradoxes (two of the same person from completely different timelines running around, Riders from futures that theoretically should not exist showing up, the heroes receiving powers either earlier than recorded or that they never obtained at all, etc) to the point that the universe can't keep up with maintaining one of the rules (namely, the rule that there can only be one of any particular Kamen Rider('s power) arround at the same time).
• Transforming Mecha: Some Ride Armors are more than just, well, armor. The Fourze Armor takes the form of a rocket (and Sougo can use that formation while wearing it); and the OOO Armor is built out of hawk, tiger, and grasshopper robots. The Gaim Armor, like both the original's Orange Arms and when Drive borrowed his powers as Type Fruit, unfolds from a giant mechanical orange. And the giant Gaia Memories on the Double Armor can transform into humanoid mecha.
• Wham Episode: Like many recent Rider seasons, there's a good few of these, but with a few standout examples:
  • #12, the ending of the Gaim arc, reveals that for the first time, something has happened that wasn't according to Woz's record of the future. This establishes that the show up until now has been enacting a Stable Time Loop, and therefore that Geiz and Tsukuyomi are actually on the path to causing the birth of Oma Zi-O by going back in time to try and stop it.
  • #15 demonstrates The Un-Twist in splendid fashion. The show up to that point has had Sougo fervently disbelieve that he could ever become Oma Zi-O, and he's so different from his future counterpart that Geiz, Tsukuyomi, and even much of the audience expected it to be revealed that he'd been framed, especially after Ex-Aid and Build both had premise-shattering reveals at this point of their respective runs. Instead, the twist is that there is no twist, as Sougo is at last forced to confront the horrifying reality that he truly is Oma Zi-O.
  • #27 reveals that Swartz not only orchestrated the bus crash that killed Sougo's parents ten years ago, but he's also behind Sougo's desire to be king, bringing all the children from that bus to the Day of Oma to see who had the ability to become Zi-O. This also explains why he just shoves Another Watches into random people instead of scouting them like his two allies. He already HAS his candidate for king, and he always did.
  • #46 sees Swartz finally lay out his Xanatos Gambit for Sougo, and how thoroughly Sougo has been manipulated for his entire life. His only real friends are time travelers from timelines that are mutually incompatible with his own, and the only timeline in which they all coexist is the one that brought them together to try and kill him. For Sougo's friends to live, he must become Oma Zi-O.
  • #47 has things go From Bad to Worse. Reality finally starts collapsing under all the time paradoxes, causing the Ridewatches to break, alternate worlds to start merging together, and monsters from all across Heisei Kamen Rider history to start showing up and terrorize the people. As a result, Tsukasa decides that he needs to destroy the world.
• Wham Line:
  • From the Heisei Generations Forever trailer;
    Kamen Rider is nothing but a television show, a fiction.
  • In #15, Sougo reveals that ever since he was a child, he had a dream about giant robots destroying the city, people dying left and right, and a mysterious man telling him to become a king so he could save the world. After Tsukasa flings him fifty years into the future, Sougo meets a man who introduces himself by describing the exact same dream, revealing himself as Sougo's future self and Ōma Zi-O.
  • #47 has this line that will shock you once you watched Kamen Rider Decade...
    Tsukasa: This world...shall be destroyed.
• Wham Shot:
  • Black Woz's investigation of the fateful bus accident that Sougo and Hiryu were in ten years ago reveals that the listed driver for that bus is Tsukasa Kadoya.
  • #30. Daiki/Diend's real target was White Woz's reality-rewriter tablet, and he finally reveals his accomplice behind one of those shimmery portals from Decade. Except it's not anyone from that series. It's Oma Zi-O.
  • #43. Diend freezes time, allowing Swartz to come over and take Decade's power, finally able to obtain the power of Another Decade.
• Whole-Plot Reference: Tsukuyomi distancing herself from Sougo as a result from getting more wary as a result of the massive amount of power he is shown to possess (turning back time and seeing dreams he makes come true) is reminiscent of the police and public becoming more wary of Kamen Rider Kuuga from his growing power after he destroyed an entire city block in Rising Mighty form.
• World-Healing Wave: In this case, Multiple World Healing Wave, as Sougo turns the immense destructive powers of Ohma Zi-O into the power of creation, in order to restore the Rider worlds to their original, unblemished states in the finale. He loses those powers afterwards, as he has no use for them anymore.
• Wrong Context Magic: Some previous Riders have aspects to their powers that interfere with the usual rules for Ridewatches:
  • Den-O is immune to time alterations and therefore keeps his powers despite the existence of Another Den-O (however, he still loses them when they're transferred to the Den-O Ridewatch).
  • Decade similarly keeps his powers despite the creation of his Ridewatch, though again, he can have them stolen to create the Decade Anotherwatch. Late in the series, he reveals that this is because he only stored half his powers in the Ridewatch, and the Anotherwatch took the other half. But even with his Rider powers tied up in the Watches, some abilities remain intrinsic to him.
  • Interestingly, Gaim is not one of these; despite ascending to godhood in his own series, he's still completely depowered by Another Gaim. He may have allowed this voluntarily, though his powers have been shown to not control time very well.
  • The future Another Riders and Miridewatches also operate by different rules than the normal ones. They aren't clearly defined, but it seems like each Rider/Miridewatch has its own set.
  • Another Kikai is created by a strange beetle instead of an Anotherwatch, which causes complications when the Riders try to defeat it. Meanwhile, the Time Jackers spend their time trying to make a usable Watch with its powers.
  • Ryuga's origin involves both time loops and a pocket dimension making it impossible for the Riders to get his Ridewatch the (then-)normal way by going back in time and giving him a blank Watch that absorbs his powers by the present day. They're forced to upgrade to Zi-O II, which flat-out overrides the Takes One to Kill One restrictions.
  • The Agito tribute is affected by the fact that a monster version of Agito already exists: the rules of the Seed of Agito are that there can only be one Agito, and everyone else with the Seed gets lesser or warped powers. When Agito dies, then someone else with the Seed inherits the true Agito powers. In Zi-O the Agito Anotherwatch works by granting its host the Seed and triggering its imperfect form, which can then be spread to others as The Virus; and like the inheritance rules of the old series Another Agito can become the Agito when the previous host can't.
• Xtreme Kool Letterz: A lot of the romanization of the names in this show prefer the use of "zi" instead of "ji".
• Your Terrorists Are Our Freedom Fighters: The Time Jackers are described as freedom fighters from the future, but not only do they want to ensure the birth of Ōma Zi-O, they want him to be even worse and are trying to find candidates other than Sougo to replace him as the Demon King.

Kamen Rider Zi-O: Supplementary Plans provides examples of:

• All There in the Manual: The Supplementary Plan web specials feature the cast explaining things in the world of Zi-O, such as their Meaningful Names and how Another Riders work.
• Animated Actors: A live-action version. The Supplementary Plan episodes operate on a bizarre level of reality in between Medium Awareness and No Fourth Wall, where the cast are fully aware that they're fictional characters and make reference to Toei, toy companies, specific writers and directors, and at one point they even spin the camera around to show the production crew...but they're still the fictional characters rather than the actors. #10.5 ends with Geiz flubbing and referring to Sougo as "Okuno-kun", which prompts the director to call "Cut!" and Sougo to gently tease "You can't do that!"
• Ascended Meme: #14.5 has Sougo, Geiz, Woz, and Tsukuyomi shout "Onore Dikeido!" to Tsukasa at the end of the episode.
• Bellisario's Maxim: Invoked as one of the rules of the World of Zi-O, as explained in #2.5. When Ryuga asks about inconsistencies in Build's altered timeline, Sento replies that one of the rules of time travel is "Don't ask unnecessary questions about adult circumstances." Geiz brings it up again in #13.5 when Takeru uses a hand puppet of Yurusen, presumably referencing the fact that neither the character nor her voice actress Aoi Yūki came back for Zi-O.
• Blatant Lies: In #6.5, Takumi and Kusaka try to give explanations why combining the Fourze and 555 tributes are a natural fit, such as Fourze's limb symbols being an intentional tribute to the 555 Riders (which falls apart because Fourze has a fourth square symbol that doesn't match anyone) or both shows and Zi-O being about kings (555 involves hunting for an Orphnoch King, while Fourze... has an "oh" ("king") sound in his name). ^note The real reason was much more mundane - 4 is followed by 5. Also, the space theme of Fourze gave a solution Faiz's Worms invading.
• *Bleep*-dammit!:
  • Heard in #6.5, which discusses the Fourze actors being unavailable. Sōta Fukushi and Ryō Yoshizawa's names, plus the title "Bleach" are bleeped just enough to cover Toei legally. Spoofed at the end of the segment when they discuss Shinichirō Shirakura, producer for both Zi-O and 555 (among other Rider series): he's called "Shirakura-P"^note a common Japanese nickname for producers but the bleep comes after the P, meaning it doesn't actually censor anything at all.
  • It's used again in #11.5, to cover Tsukuyomi when she references Doraemon.
  • And again in #13.5, first when Tsukuyomi compares Yurusen to a character from GeGeGe no Kitarō, and again when Sougo compares Ghost's "collect 15 Eyecons to get a wish" plot to Dragon Ball. Geiz then tells him that if they keep referencing Shonen Jump properties like Bleach and Dragon Ball it'll just get bleeped out...and Sougo points out that his rant is gonna get bleeped too.
• Brief Accent Imitation: In #13.5, Tsukuyomi dreamily asks if "the Nation's Boyfriend" (Kamen Rider Drive star Ryoma Takeuchi) will be appearing in the show. Takeru drops into an impression of Takeuchi as Shinnosuke Tomari, even referring to Tsukuyomi as Kiriko, and basically tells her "don't ask too many questions about it".
• Depending on the Writer: Lampshaded in #10.5, where the characters complain that their characterization seems off and realize that a different writer had come in on the last couple episodes. And that the director didn't keep things straight because, looking forward through #12 and Heisei Generations Forever, there have been seven directors already. Sougo concludes that it's up to the cast to protect their own characterization if the staff won't.
• Foiler Footage: Discussed In-Universe in #16.5. Sougo, Geiz, and Tsukuyomi wonder how Toei managed to keep the "big secret" of Heisei Generations FOREVER (namely, Takeru Satoh reprising his role as Ryotaro Nogami for the first time in ten years) from being spoiled. Woz explains that the producers used a few tricks, like leaving those scenes out of the shooting script (marking them with "To Be Added") and filming in secret with a skeleton crew on days where no filming was scheduled^note For example, on days that were set aside in case regular filming was rained out. The three heroes remark that they didn't even realize what was happening and actually get offended that Toei would freeze them out like that.
• Freeze-Frame Bonus: #11.5 reveals that there are a number of items taken from past Rider series scattered around the Kujigojido shop. The cast specifically points out a science-themed clock from Build and challenges viewers to find the rest.
• Future Slang: Spoofed in #15.5, where Tsukuyomi refers to Sougo as "basic", followed by a pop-up window that explains we aren't really sure if they still use 2010s slang in 2068.
• Hostile Show Takeover: In #15.5, Sougo explains that he can't give up his belt because he's the star of the show. Geiz then reveals that he wants this to happen, so the show can be replaced by "Kamen Rider Geiz", complete with a debut trailer. Tsukuyomi follows up with a trailer for "Kamen Rider Tsukuyomi".
• Meaningful Name: #1.5 explains the names of the main trio:
  • As explained in Double-Meaning Title, Zi-O, in addition to meaning "Time King", can also be read as a 2 and a 0, making 20. The epithet of his future self, Ōma Zi-O, is an anagram of "maō", or "demon king".
  • Tsukuyomi is named after the goddess. However, the name can also be read as "counting moons", in other words, a way of telling time. It also means "moon phase", which becomes more relevant later on since her actual Rider form has a crescent moon motif in the mask.
  • Geiz is a pun off of "gates". As Woz explains, it's related to kings because kings were traditionally viewed as a sort of gateway, like how a pharaoh was seen as a gate between the people and the gods. (The cast then asks him why it's "Gates", plural, but he doesn't have a good answer.) Geiz himself claims it's because it makes him sound rich. Although not mentioned in the episode, geiz also a German word for "stinginess" or "miserliness".
• Merchandise-Driven: Specifically addressed in #9.5. Sougo asks why Kuroto Dan is in the Kamen Rider OOO arc and initially concludes that it's because of the toy releases^note The limited-time offer for the Genm Ridewatch started on November 3rd 2018, in the middle of the OOO arc and wonders if that means the entire series is at the beck and call of toymakers. However, Woz and Kuroto explain that it's the other way around and that merchandise release dates get shifted around in order to line up with the episode airdates.^note The specific example given is the second wave of OOO-themed toys, which came out on November 10th, the airdate of #10 In reality, the reason for Kuroto's appearance was because it was the only time actor Tetsuya Iwanaga was free to record his cameo.
• No Fourth Wall: The Supplementary Plans shorts are like this, with the actors still playing their characters but walking around with scripts in hand and openly acknowledging that they're in a TV show.
• "Not So Different" Remark: Daiki compares Masato to Geiz in NEXT TIME, asking if he became a Rider unaware of the consequences that would follow. His response?
  "I don't even feel like dignifying that with an answer."
• Once per Episode: Almost every episode starts off with a character reading their script and reciting "(Character) was fraught with anxiety."
• Out-of-Character Moment: In #15.5, Geiz complains about how the Supplementary Plans episodes will make him say things that he would never say normally, like the suggestion of blowing up Toei Studio back in #3.5.
• Rage Against the Author: Sometimes the cast takes the opportunity to gripe about the show's staff.
  • After Hora claims in #3.5 that there's going to be a Rider War to determine the new king, the main trio go this route to try and prevent it. Tsukuyomi proposes simply appealing to the writers, while Geiz wants to kill the producers. Sougo takes it a step further and proposes destroying Toei studio.
  • #6.5 has Kusaka blame producer Shirakura for the awkwardness of how the Fourze and 555 tributes were mashed together.
  • #7.5 has the main characters complain that many of the scenes that they shot ended up not going into the final product and/or were cut out. Sougo decides to confront the directors himself. The result? The entire premise of Sougo becoming Oma Zi-O was cut out.
  • In #10.5 the main characters express frustration with the staff for not being able to keep their characterizations straight.
• Red Herring: #3.5 claims that the series is heading for a Big Badass Battle Sequence where all 20 Heisei Riders were going to fight it out for the right to become king. This never happens, nor is it even hinted to happen in the series itself.
• Self-Deprecation : The web exclusive series Supplementary Plan has the characters complain about the problems of the series production
• The Un-Reveal: In #15.5, the "Kamen Rider Tsukuyomi" trailer gets shoved away by Sougo just before it would have revealed what Tsukuyomi's rider costume looked like. When she's introduced in the show proper, her watch, mask, and color scheme are all different than what was shown in the Supplementary Plan, meaning the alternate design teased there never got a reveal at all.

---

"And thus marks the last page of the history of the Heisei Riders."

---