The Chessmaster: During the events of The Movie, set in a post apocaliptic setting, he purposefully stirs up fights between the ZECT and Neo-ZECT Riders, in order to lure out the legendary Golden Rider Caucasus and take a hold of his Hyper Zecter. He then uses the Hyper Zecter to travel back in time and prevent The End of the World as We Know It. (or at least minimizing the damage of said disaster)
Not So Stoic: Try putting your finger into a fish without shouting in the credits of the movie. And speaking of the film, he loses it and grieves after Hiyori dies, making him a Tragic Hero in the process. Eventually fades from existence knowing full-well Hiyori will be saved.
Red Oni, Blue Oni: The blue to Kagami's red. Ironically, his Rider suit is red (but his eyes are blue) and Kagami has a blue suit (with red eyes)
I Just Want to Be Badass: Kagami wanted to become a Rider so he can fight Worms. He does take a role of TheBee, but temporary. He eventually Took a Level in Badassand becomes Kamen Rider Gatack when he was emotionally pushed to his limit when Makoto, who is a Worm, double crosses him.
Fallen Princess, Impoverished Patrician: When he finds out that the Discabil family fortune has all but dried up. He becomes bound and determined to restore his family name to prominence, starting out by working a job at a soba stand. Previously, he had been a...
Lethal Chef: Unless your name is Tsurugi and Tendo's evil twin.
Suspiciously Similar Substitute: Hiyori's actress, Yui Satonaka, developed health issues and took a break after filming for The Movie ended. As a result, Renge was written in shortly after Hiyori was Put on a Bus to introduce the Hyper Zector, and took her place in Bistro La Salle.
Big Bad: In the movie, where he willingly made a deal with the Worms
Dark Secret: Keeps it under wraps that he and Tendou's father chose their own sons to wield the Rider System before they were even born.
The Dragon: In the movie, where he and Riku made a deal with the Worms to annihilate humanity.
For Science!: He's not above conducting experiments on an innocent young boy to unlock the true nature of the Rider System.
Not-So-Harmless Villain: Whatever Mishima was doing was ignored in favor of the goal of destroying all Worms and the saving Hiyori subplot. Come episode 47, Mishima becomes a One-Winged Angel and is revealed to be a converted Native!
The Starscream: Getting tired of Riku's bullshit, he decides to take things into his own hands, becoming the Final Boss in the process.
Bistro La Salle
Catchphrase: "Why me?" or "Why do I have to?" note Nande boku ga?
I Am a Monster: This was her reaction to discovering that she is a Worm.
Locked Out of the Loop: Remains blissfully unaware of everything Tendou is doing in spite of being acquainted with members of ZECT.
Meaningful Name: Lampshading Tendou and Tsurugi's Meaningful Names, she has one of her own spoken in lieu of Tendou's Catchphrase: "The beautiful girl who walks on the path of heaven, and makes trees and flowers beautiful." note Ten no michi wo iki, ki to hana wo utsukushii bishoujo.
Morality Pet: Put Juka in danger and you'll be dealing with Tendou.
Only Known by Their Nickname: Prior to receiving her memories back, she was referred to as "Gon", short for "Nanashi no Gonbei" (nameless person). Come the end of the series, however, she prefers to be addressed by her real name, Yuriko.
Curb-Stomp Battle: Easily defeats Hercus with his Hyper Zecter, which uses Hyper Clock-Up. He also handles Kabuto and Gatack with no problem. Until Gatack catches his foot mid-attack, allowing Kabuto to steal the Hyper Zecter. Then Kabuto defeats him in return just after using Hyper Clock-Up a few minutes backwards, and Hyper Kicks him to annihilation.
Evil Counterpart: The Caucasus Zecter is one of Kabutech Zecters, which is based on Kabuto's.