Gate Keepers 21 is a Japanese six-part sequel OVA series to the Gate Keepers series, possessing a darker and more serious plot than its predecessor. Some of the questions left unanswered in the TV series are answered in this sequel. Linking the two series are the characters Reiji Kageyama, Yukino Houjo, and the former Far Eastern AEGIS Headquarters setting, Tategami High School.
31 years have passed since the Far Eastern Branch of AEGIS and the Invaders waged war in Japan. The heyday of growth and prosperity has passed, the crime rate has increased, environmental problems have worsened, and the international situation has become increasingly unstable. Coupled with the decline in the morals of the Japanese people comes the emergence of a new type of Invader — one that can absorb ordinary humans into its ranks.
Though they have been officially disbanded and discredited, the remnants of AEGIS have formed a clandestine network to hunt down the Invaders, led by the antisocial Ayane Isuzu, who collects the crystal remains of Invader in exchange for money doled out by the mysterious Reiji Kageyama.
Gate Keepers 21 contains examples of:
- All There in the Manual: Bad news: You have 31 years of catching up to do between GateKeepers and this. Good news: There are some novels and a video game bridging the gap. More bad news:
None of them are in English. - Badass Bookworm: Ayane Isuzu is quiet, ranked third in the second-year level of her high school, spends most of her time reading and sitting in front of her laptop. She is also the leading cause of Invader death by blunt cell phone trauma.
- Blow You Away: Ayane wields the same Gate of Wind as her father Shun did.
- Body Horror: Humans' transformation into Invaders varies: sometimes the human visibly mutates into one, and sometimes the Invader climbs right out of the unfortunate person's overstretched mouth, leaving a wrinkly husk of skin and clothes on the ground. And then there's Chinami and Nao, who turn by having their normal human skin flake off while their bodies mutate into monstrous Invader proportions — all while we get slow, loving shots of the process.
- Bounty Hunter: AEGIS employs 'Invader Hunters', who may or may not be Gatekeepers (those who aren't use Imitation Gates) and pays them according to the number of invader crystals they collect.
- Cerebus Syndrome: There are many fans of the original series that don't much care for the Darker and Edgier feel of the sequel series.
- Continuity Nod: When Ayane and Miyu launch the UP-15 from the self-destructing AEGIS base, Yukino does the "Ooh, intense!" thing that accompanied AEGIS vehicle launches in the original series. No panty shots, though.
- Darker and Edgier: Compared to the prequel, things look a lot grimmer. Many of the previous cast is dead, some of them killed while fighting the Invaders, and the Invaders show no signs of letting up. It's also revealed that using the Gate powers carries a hefty toll on the body, as shown by the remaining Gate Keepers from the prequel.
- Dark Is Not Evil: Kageyama, though he also happens to have elemental light as a power, so...
- Demonic Possession: Any and all non-Gatekeeper humans who succumb to any dark emotion open themselves to possession by the Invaders.
- Disappeared Dad: Shun doesn't make an appearance in this anime, and the interquel novel reveals that he's died fighting the Invaders..
- Dude, She's Like in a Coma: Ayane Isuzu is kissed while comatose by Big Bad Stalker with a Crush Ghost Girl, while the former's boss and partner watch helplessly.
- Equivalent Exchange:
- Gates run on this. Kageyama points out the fact that most Gatekeepers have suffered some kind of trauma earlier in life. Furthermore, Kageyama's own Dark Gate has, over the years, eaten most of his insides, as well as a literal arm and leg, forcing him to take extensive medication and use Artificial Limbs, the reason why Yukino never ages is because her Gate has consumed her 'time', and he also speculates that Ghost Girl's has already consumed her entire body.
- Ayane is afraid of being consumed by her gate, and so uses false gates until told that they simply don't have the power needed.
- Everybody's Dead, Dave:
- Almost the entire cast from GateKeepers die (or are simply written out) in the backstory.
- Episode 5 sees the Ghost Girl's plan come to fruition: turning every non-Gatekeeper in the city into an Invader.
- Everything's Better with Sparkles: Miu's Gate of Leap gives off quite a lot of them.
- Gratuitous English:
- "This is your power. It's a miracle!"
- GAAAYY-TOOOOHH OHHH-PUUUNN!!!
- Heel–Face Turn: Reiji Kageyama, the Big Bad of the original series, is now the head of A.E.G.I.S.
- Hopeless War: In contrast to the ending of Gate Keepers, the Invaders have continued to take over at least half of humanity, there's no way to actually win, and the very power used to fight the invaders will kill the users. Or worse. Ouch. The ending, however, has the tables turn in humanity's favor, with most of the Invaders wiped out. Granted it required a Reset Button, and that the remaining ones are still in the open, but still...
- Improbably Female Cast: The only male characters are a Supporting Leader, the two Dragons, and an Inspector Javert who doesn't seem to serve any purpose other than
padding. - In a Single Bound: Miu's Gate Power is called Flight but is really more of this trope.
- Inconsistent Dub: The English dub of the original Gate Keepers refers to Akuma Hakushaku as "Baron Akuma." In this one, he is called "Count Akuma" instead.
- Lamarck Was Right: Ayane inherited her power from her father Shun, who in turn inherited it from his father.
- Magical Girl: Played pretty straight with the Gatekeepers, but also parodied by a "film-in-film" Miu and her friends watch.
- Mood Whiplash: In contrast to the previous anime, don't expect much in the way of bright and happy. They really made sure that the days of the "original" Gatekeepers were long over.
- Non-Indicative Title: Gatekeepers 21 does not take place 21 years after the original series; it takes place 31 years later in 2001, the start of the 21st century.
- #1 Dime: Ayane's bell. Depending on how her surname is spelled in Kanji, could veer into Meaningful Name territory, as one spelling of "Isuzu" means 'Dependable Bell'.
- Oddly Named Sequel 2: Electric Boogaloo
- Older and Wiser: Several characters from the original GateKeepers, now grown up, act as commanders, mentors, and parents to the new cast.
- Our Hero Is Dead: At the end of episode 4 of GK21, Ayane is shot from behind on the way home from killing Count Akuma.
- Powers as Programs: Advancements in technology have allowed members of AEGIS to emulate Gate power, encoding them into cell phones. This allows even non-Gatekeepers to have a fighting chance against the Invaders.
- Psycho Lesbian: Ghost Girl, the Big Bad, totally has it in for Ayane.
- Revenge by Proxy: Count Akuma's goal since Shun is unavailable, he'll go for the next best thing: Shun's own daughter Ayane.
- Reverse Polarity: Inverse Gates trigger in high emotional states, doing the opposite of what the user's original Gate does. When the Big Bad, whose normal Gate power is to erase things, gets pissed off when Ayane destroys her Soul Jar, the last thing she does before fading away is use her Inverse Gate, which causes everything to go back the way they were. Satoka points out the possibility that in her anger, she forgot that the Inverse Gate does the exact opposite of the regular gate.
- Sailor Fuku: Miu brings Yukino a seeraafuku for a school uniform. Why not get her an actual uniform of Miu's school? Well, because.
- Shout-Out: The crane game has characters from Parappa The Rapper, Azumanga Daioh, and Sgt. Frog, among others.
- Spider-Sense: Kageyama uses his Gate of Foresight to make lots of money in the financial world, which he uses to fund AEGIS and pay Invader Hunters.
- Strong Family Resemblance: Ayane bears a resemblance to her aunt Saemi, Shun's younger sister, except she wears glasses. Saemi furthermore resembles her mother after growing up.
- Unknown Rival: Tachikawa Satoka spends most of her free time talking to/critiquing/lecturing Badass Bookworm Isuzu Ayane only to get ignored, or ditched when her back is turned, much to her chagrin.
