- Written by : Kento ShimoyamaDirected by : Takayuki Shibasaki
- Woz: As it is written in this book, Sougo Tokiwa embarks on a path which leads him to become the Overlord of Time, Oma Zi-O.
Now, that future is on the precipice of becoming reality.
Only three pages remain... until the end of the world.
After the death of Michal Minato, Swartz continues to provoke Sougo. He says that Sougo must choose wisely as the end of the world is near. Suddenly, the earth rumbles and a wall appears from underground, seemingly dividing Japan. Some robot-like soldiers and blackened monsters also appear and attacking citizens. As Sougo watches helplessly, Swartz disappeared.
Back at 95 DO, Geiz, Tsukuyomi and Woz are wondering where Sougo went after the battle against Swartz and his Dark Riders. Junichiro offers them food, while saying that Japan is divided by a wall and maybe Sougo's on the other side. Suddenly a bruised Sougo comes back and immediately inspects his Ridewatches. Just as he thought, the Build Ridewatch is broken and thus, the wall just as he seen in 2017 while he's with Sento Kiryu, appeared. Woz explains that said wall is the Skywall, from Kamen Rider Build's world. After that, Sougo asks Tsukuyomi to come with him.
Sougo explains that he knows Tsukuyomi's real name as Alpina and broke the news of Minato's death. He also relays Swartz's information to his friends. As Geiz tells him to think carefully, Sougo took Tsukuyomi away.
Sougo and Tsukuyomi arrive before Tsukasa Kadoya. Sougo asks the dimension-hopping Rider to take them to Tsukuyomi's timeline to learn about Swartz's true goal. Tsukasa agrees but warn them because they may not like what they learn.
In the city, Geiz and Woz are helping citizens from Guardians and Smashes. They transform to Geiz Revive Goretsu and Woz Ginga Finally to take them out. Then, Futo Tower and Yggdrasill Tower appear in the city, and with them, an army of Dopants and Inves. As they wondered what to do, a Heavy Acceleration field affect them. True enough, some Roidmudes that Woz knows as Kamen Rider Drive's enemies appear. They transform into Shippu and Wakusei respectively to counter the slowing effect and destroy the enemies, until suddenly, a purple and heavily-armored Roidmude arrive.
The Roidmude general takes out Geiz and Woz, and transforms back into his human-like form, Chase. He declares himself as the reaper of all Kamen Riders. Geiz, who knows about Kamen Rider Drive from Krim Steinbelt, asks if Chase knew Kamen Rider Mach, Go Shijima. Chase doesn't know about Go however, and explains that in his world, there are no Kamen Riders. As Chase moves to attack Geiz, the future rider says that he contradicted himself. If there are no Kamen Riders in Chase's world, how can he become the enemy of all Kamen Riders, how can he become the enemy of something that doesn't exist? Hearing this, Chase's memories about Kamen Rider Drive's world, his death to be precise, returned and he doubled over in pain.
As Geiz and Woz are on the run from the battle, they see Mirror Monsters emerge. Woz theorizes that the worlds of Kamen Rider are beginning to merge together in this world, triggering the end of the world...
Meanwhile, Tsukasa takes Sougo and Tsukuyomi to the year 2058, to Tsukuyomi's house. They meet young Alpina and ask her about her brother Swartz's true goal. Suddenly a young Swartz appears and said he will explain. He explains that there are many worlds and each world have their own Kamen Riders. As the existence of his world is being threatened by the other worlds, Swartz plans to fuse all the other worlds into one and then destroy it, to save his world. Hearing this seemingly noble goal, Tsukuyomi drops her hostility. But, as Swartz prepares to leave this world with his sister, Sougo asks if he's still plan to save his world even if his sister is more powerful than him. Realizing that Alpina is indeed stronger, Swartz goes berserk and attacks Sougo and Tsukuyomi.
He throw them outside and Sougo asks Tsukuyomi to defeat Swartz, the source of all these conflicts. But, Tsukuyomi cannot do it, and Swartz blasts her with time power to kill her, until Tsukasa stands in its path and struck fatally. On his dying breath, Tsukasa says that Tsukuyomi is a very important people and thus cannot be killed...
Suddenly, Daiki Kaito appears from a dimension wall. He chased Swartz away and goes to Tsukasa's body, not to mourn, but to help him. He takes out his "treasure", the Another Zi-O II Watch and uses its time reversing power to return Tsukasa to life. Kaito succeeds in returning Tsukasa to life, but the Anotherwatch possesses him, turning Kaito into Another Zi-O II. As Tsukasa is attacked by the Another Rider, he asks Sougo to return his Decade Ridewatch. After Sougo tosses it to him, Tsukasa pushes the button on the Ridewatch. With that, Tsukasa's Neo Decadriver and his rider power return. Tsukasa whisks Another Zi-O II alongside Sougo and Tsukuyomi back to 2019. Kaito tells Tsukasa that he thought Swartz had taken his Rider powers. Tsukasa explains that he had anticipated something of the sort, and thus he had created the Decade Ridewatch by putting half of his Rider powers into it as insurance.
As the Another Rider overwhelms him, Tsukasa takes out Zi-O Kamen Rider Card and transforms i to Decade Zi-O Form. He asks Sougo ti get in on the action, and Sougo transforms into Grand Zi-O. The duo of Zi-O defeat Another Zi-O II and finally destroy its Ridewatch as Kaito returns to his human form. As Tsukasa help his rival to stand, more monsters and aberrations appear in the sky. The Grand Zi-O Ridewatch also disappears as more Ridewatches are broken. Tsukasa then declares that he will destroy Sougo's world, much to Daiki, Tsukuyomi, and Sougo’s surprise...
List of Episode Tropes
- Back from the Dead: Tsukasa's death doesn't stick as Daiki uses the Zi-O II Anotherwatch to undo it.
- Call-Back: To the first episode, as Sougo states he knew something happened to the Build Ridewatch when the Skywall appeared and he remembered them when he accidentally visited 2017.
- The Chessmaster: Tsukasa reveals that he expected to lose his powers as Decade thus he stored half of his powers in the Decade Ridewatch just in case.
- De-power: Late into the episode, Sougo loses access to the GrandZi-O Ridewatch as more Ridewatches continue to crack in 9-5Do.
- From Bad to Worse: It's bad enough that Swartz has become Another Decade and has now reclaimed all the time powers he passed to the Time Jackers. Now the worlds are merging with every RideWatch that breaks. In succession; the Skywall from Build, complete with Clone Smash and Guardians. Then Roidmudes of Drive appear, lead by an Another World Mashin Chaser. Then the Fuuto Tower and Yggdrasill Tower of W and Gaim appear, causing Masquerade Dopants and Elementary Inves to appear. Then the Mirror World of Ryuki merges with Earth, causing the sky to be filled with Mirror Monsters. Finally, the GrandZi-O RideWatch fades, and by then, OOO's, Fourze's, Hibiki's, and Kabuto's realities have also fused, forcing Decade to destroy the world.
- Godzilla Threshold: Things have gotten so bad that by the end of the episode, Decade decides the only thing to do is destroy the world.
- Heroic Sacrifice: When Swartz tries to kill Sougo and Tsukuyomi in 2058, Tsukasa steps in and takes the hit for them, dying in the process. Fortunately for Tsukasa, Daiki was able to make Swartz retreat and reverse his death using the Zi-O II Anotherwatch.
- Killed Off for Real: The Zi-O Anotherwatch is finally destroyed once and for all in this episode.
- Merged Reality: As a result of the Ridewatches breaking, the various histories and powers of the Riders are fusing with Sougo's world. By the end of the episode Build's, Double's, Gaim's, Drive's, OOO's, Fourze's, Hibiki's, Kabuto's and Ryuki's realities have already fused.
- Not-So-Well-Intentioned Extremist: 2058 Swartz states his goal is to save his world from being destroyed, but when he is asked to consider if Tsukuyomi grows stronger than him, he goes berserk as he thinks he deserves the throne.
- Re-Power: Sougo returns the Decade Ridewatch to Tsukasa as he's being attacked by Another Zi-O II, which lets Tsukasa become Kamen Rider Decade again.
- The Reveal: It's revealed that Sougo traveling into the past and obtaining the powers of his Kamen Rider predecessors created parallel worlds where the evil forces they fought were victorious. Now, all those worlds are merging into Sougo's.
- Time Crash: We finally see the culmination of the various paradoxes that have happened over the course of the series: early in the episode the Ridewatches start cracking, unsealing the powers and history contained within them including that series's respective monsters but seemingly not the associated Rider.
- With Great Power Comes Great Insanity: Daiki using the Zi-O II Anotherwatch to revive Tsukasa causes him to be forcefully transformed into Another Zi-O II.
