"The train of time, DenLiner. Will its next stop be the past? Or the future?"
Kamen Rider Den-O is the 2007-2008 series of Kamen Rider and the eighth installment in the Heisei Era.Ryotaro Nogami is the unluckiest guy in the universe. But his life changes on the day he stumbles across a mysterious train pass that allows him to board the DenLiner, a Cool Train that travels through time.Just as he is recovering from the shock of this, he is suddenly possessed by a monster known as an Imagin: shapeless creatures from the future that take on forms based on the ideas within their host's imagination. The Imagin make contracts with their hosts to gain physical bodies, offering to grant them a single wish. Once the wish is fulfilled, they can then use their host as a gateway back through time, aiming to destroy the past to seize control of the future.However, it turns out that Ryotaro is a Singularity Point, a person immune to any changes to the timeline and able to resist the possession of his Imagin. He is soon corralled by Hana, a mysterious passenger of the DenLiner, into using his power as a Singularity Point and his Rider Pass to transform and fight the hostile Imagin invaders as Kamen Rider Den-O.While Den-O's base form (Plat Form) is incredibly weak, Ryotaro can relinquish control of his body to an Imagin who has possessed him and power up. His first Imagin, a Hot BloodedBoisterous Bruiser called Momotaros, transforms Den-O into the red Sword Form. Together, They Fight Crime.The plot thickens when Ryotaro discovers that Yuuto Sakurai, his sister's missing fiance, is hiding in the past for reasons unknown, and somehow linked to the Imagin attacks. Just as Ryotaro goes to confront him, he is stopped by none other than a younger version of Yuuto Sakurai. This version of Yuuto is brash and cocky, bringing with him his own Time Train called ZeroLiner and the ability to transform into Kamen Rider Zeronos.Though it had average television ratings, Den-O proved to be a massive hit in Japan, spawning multiple character song CDs, a spinoff anime starring the Imagin and eightmovies (along with supporting roles in three other movies), which is practically unheard of for a series that was only designed to last a year. The movies are:
Ore, Tanjo! (I'm Born!): A rare aversion to the Kamen Rider tradition of one Non-Serial Movie per series, this film caps off the show's second act and revolves around the time-traveling bandit Gaoh and his theft of the DenLiner, which he wants in order to find the forbidden "God's Line" and the powerful Time Train resting at the end. The series spends a couple of episodes teasing at the movie just before its release, then dedicated the next episode after the film's opening to dealing with the aftermath.
Climax Deka: Set after the series, this movie sees Team DenLiner setting up a detective agency when a rogue Imagin, Negataros, steals the Owner's Liner Pass and begins forming an evil organization. Nominally a Cross Over with Kamen Rider Kiva, the "crossover" is limited to a couple of brief scenes featuring Wataru and a Big Damn Heroes appearance by Kiva near the end of the final battle.
Farewell Den-O: Final Countdown: The DenLiner crew must contend with the villainous Shiro and his minions, including Kamen Rider Yuuki. With Yuto injured and Ryotaro MIA (possessed by the Ghost Imagin and forced to be Yuuki), the crew must turn to Kotaro, Ryotaro's Grandkid From The Future, AKA New Den-O, who doesn't exactly think too highly of Gramps or his Imagin partners.
Cho-Den-O and Decade: The Onigashima Battleship: The first in the Cho-Den-O film series, this movie ties directly into the Den-O arc of Kamen Rider Decade and sees the DenLiner crew, with brief support from Tsukasa Kadoya/Decade, battling a pair of Oni brothers/rogue Kamen Riders who seek to uncover a legendary and powerful battleship. Also features nominal cameos by Kiva characters, (something of a nod to Climax Deka, also supposedly answering a few continuity issues with the aforemention Decade) as well as Riders from Agito, Ryuki and the KabutoNon-Serial Movie summoned up by Decade's rival Daiki Kaito/Diend.
Kamen Rider × Kamen Rider × Kamen Rider The Movie: Cho-Den-O Trilogy: Three separate feature length films released in the span of a month, each one attempting to resolve plot points for a different set of characters, none of them are Den-O himself;
Episode Red: Zero No Star Twinkle focuses on Yuto being forced to choose between two jobs equally important to protecting the timeline - preserving his future self's relationship with Airi, and stopping an Imagin from stealing the DenLiner.
Episode Blue: The Dispatched Imagin is NEWtral focuses on New Den-O and his relationship with his Battle Butler Teddy, while having them battle a new Imagin and deal with a young woman and a supposedly Evil Twin.
Continuity Nod: The drawing of Ryotaro's parents from Ore Tanjou shows up all the way in Chou Den-O Episode Yellow. Can be considered Book Ends as these are the first and last times Takuya Mizoguchi starred as Ryotaro.
Cool Train: the DenLiner, ZeroLiner, GaohLiner, and KingLiner.
Creation Myth: Invoked in the first Movie, as Gaoh is after a traintrack that goes to the beginning of time.
Cross Over: In the movie Climax Deka, the show was briefly crossed over with the 2008 series, Kamen Rider Kiva. The fourth Den-O movie takes place after its story arc in Decade and has cameos by the Arms Monsters from Kiva.
Curb-Stomp Battle: Ore, Tanjou! has Gaoh's minions easily falling against Wing (in a separate battle), Rod, Ax, and Gun Forms. Sword Form, on the other hand, was the one in trouble, since he was facing Gaoh himself...
Dancing Theme: The Taros and Deneb (and Kivat in the Crossover movie) can be seen dancing to "Climax Jump" at the end of the opening credits.
Demonic Possession: A more benevolent version, and the only way the Taros can interact with the physical world. Played for humor in Climax Deka, where Momotaros is accidentally shunted into Wataru Kurenai's body; In the fourth movie, the Taros possess the Arms Monsters as well as DiEnd-summoned copies of G3, Caucasus, and Ohja. Tsukasa/Decade himself gets possessed by all four Taros Imagin and Sieg, while Yusuke/Kuuga is possessed by Momo and Natsumi gets possessed by the other three main Imagins at different points.
Everyone Is Related: By the end of the series we learn that most of the primary human cast is related — Yuto is Airi's future husband, and Hana is their daughter, making her Ryotaro's niece. And of course, we have Kotaro in the later movies.
Heroic Sacrifice: The Taros, Sieg and Deneb have no problem protecting the timeline from their kin, even if it means that if the Imagin race are successfully defeated, it would mean the end of their own existence as well. Prior to the final battle, Kai himself calls them out on this, asking them if it's okay for them to disappear for the sake of the humans. The one who had the problem for this setup was instead Ryotaro, leading him to go Achilles in His Tent, and even have a brief falling out with his partners.
In Episode Red, the Piggies Imagin and Den-O (as Climax Form) throw insults at each other for Sharing a Body (the Piggies Imagin with his siblings). In the end, however, they both agree that the whole concept was gross.
Also, earlier in that same movie, Urataros corrects Deneb for callimg him "Kametaros", then proceeds to call Deneb "Odebu", only to ignore Deneb's own correction.
In Episode Yellow, Momotaros (in Climax Form) derisively says "What's with that form?" when he sees Diend's Complete Form.
Identical Grandson: In the third movie, Airi, Miura, Ozaki, and supposedly older Sakurai's ancestors in 1729 are played by the same actors.
Jackass Genie: Sure, the Imagins will grant your wish... But they'll always choose the interpretation of it that will cause the most harm to you and others. Example : "I want to play soccer again!" "Okay, I'll just put the other players into hospital!" Though this could be justified due to the fact that they're not actual wish-granting genies, and thus try to find any loophole they can to render the contract "complete" and thus allow them to travel to the past.
Jidai Geki: In the first, third, and fourth movies.
The Last of These Is Not Like the Others: Episode Yellow; not only do the previous two movies focus on a Rider from Den-O, but they also involve an Imagin (outside of the Taros) as an important part of the plot. Instead, Yellow not only focuses on a Rider outside the series, but there was barely any Imagin involvement at all *
Mundane Utility: The DenLiner is, and always has been, a passenger train (time-traveling, yes, but you get the point).
Negative Continuity: Between the movies; Climax Deka ends with the group deciding to keep their detective agency open; Final Countdown makes no mention of it, and Onigashima Battleship might not even be in the same continuity as the rest of Den-O due to being a DecadeAlternate Universe.
New Powers as the Plot Demands: Towards the end of the TV series, the show decided to throw out the rule book on how exactly the Den-O system (and Imagin possession) work, and instead run on Rule Of Cool. By the time of the crossovers, there seem to be no rules: the core Imagin can freely possess and un-possess anyone at will, and can even transform into Den-O without a human host.
Retcon: The Chō Den-O Trilogy changes the rules on Imagin time travel from the show, now saying that if an Imagin successfully travels to the past, the act will destroy the contractor's past self (via dissolution into sand).
Series Continuity Error: Final Countdown has Kohana literally hand out about a half-dozen spare Rider Passes (and, by extension, Den-O Belts) to the Taros in order to let them participate in the Final Battle. This screws up the plot of Chou Den-O Episode Yellow, where Den-O losing his pass to Kaitou is treated as something terrible.
Set Right What Once Went Wrong: A rather confusing one, actually, as there are only certain things that can be fixed and it seems the only way you're allowed to do it is if you're stopping an Imagin in the process. Several times, someone in the group alters the past so that the person never made the Deal with the Devil with the Imagin in the first place, negating the wish altogether along with all the damage the Imagin caused, including what normally would've been erased for good. While things will continue as they originally did in these cases, the Victim of the Week normally comes off much happier for it. For example, a man who originally missed his band's recital and blamed himself, becoming obcessed with getting enough money to make it big had time altered so he did make the recital but his band still didn't make the cut. However, the man was now trying to make his way to the top through his own talent and hardwork instead of buying his way there and was much happier than in the original timeline.
Shared Universe: Climax Deka seems to indicate that Den-O and Kiva are set in the same 'verse, just like Kuuga and Agito. This was compounded in Onigashima Battleship with the random cameo appearances of Kiva's Arms Monsters.
Not sure if it's a shout out or would be classified as something else, but there's a very obvious parallel between Den-O and Juken Sentai Gekiranger. In Gekiranger, the team is made up of 5 people in Red, Blue, Yellow, Purple, and White. In Den-O the team is made up of 1 person with other people in him corresponding to the colors Red, Blue, Yellow, Purple, and White (for Wing Form). Also, in both shows, The Rival has the colors Green and Black related to them in some way. Interestingly, both shows aired alongside each other. An announcement of a Geki/Den-O joint promotion even ends with the five Gekiranger mimicking the poses of their respectively colored Imagin. As if returning the favor, the Imagin would later appear in promos for the Kiva Movie, but mimicking the Catch Phrases of the next Sentai, Engine Sentai Go-onger.
As pointed out in the design book Imagin: Say Your Wish..., the first few enemy Imagin correspond to Riders from Kamen Rider Ryuki: Bat to Knight, Chameleon to Verde, Crust to Scissors, Crow to Odin, Rhino to Gai. Additionally, as mentioned under Actor Allusion, the Cobra Imagin is designed to resemble Ohja, and is also voiced by the same actor.
According to Re:Imagine - Detail of Heroes 03, the villains from Onigashima Battleship are modeled Riders 1 and 2 (Goludora) and V3 (Shilubara). They also not only draw upon the gold and silver-themed heroes of Garo, but transform the same way.
Teddy displays the Newtype Flash when protecting Kotaro from bad luck.
Sliding Scale of Idealism Versus Cynicism: Den-O skews very idealistic; out of all the Imagin contractors, all but one or two are good people whose wishes were well-intentioned (or only slightly misguided, but they see the light at the end of the arc). Yuto initially thinks Ryotaro is soft for putting so much effort into helping the victims rather than just fighting the Imagin, but eventually comes around to the DenLiner crew's way of thinking. Even when Sakurai disappears into the timestream at the climax, it's treated as a temporary separation rather than Killed Off for Real.
Time Crash: Shiro's big plan in Final Countdown involves bodyjacking Ryotaro and making him destroy his own ancestors in the past, which should have this effect. It's disproved later on in Episode Yellow though.
Time Police: what the DenLiner crew see themselves as. Later, in Episode Yellow, an officer from an actual time police appears, G Den-O.
Timey Wimey Ball: "Memories are Time", which is a plot point on several occasions.
Too Long; Didn't Dub: A source of controversy in the fandom is subbing group TV-Nihon leaving as many honorifics as they can in the subs. While it wouldn't be too surprising for Japanese-themed series like Shinkenger, expressions like "cow-san-tachi" (seen in the Imagin Anime) can be jarring for fans with a minimal knowledge of Japanese. This is actually a recurring problem with said group.
Victim of the Week: Common for Kamen Rider, to the extent that future series like Double and OOO have adopted it. Even the multitude of Den-O movies uphold this tradition, so much that some unexpected examples turn up (young Ryotaro in Ore Tanjou, young Yuuto in Onigashima Battleship, and even G Den-O in Chou Den-O Episode Yellow.)