- Written By: Shogo MutoDirected By: Kyohei Yamaguchi
Takumi: Pandora’s Box, which contains incredible energy, has finally been opened. The extraterrestrial entity Evolt has used its power to achieve his complete form, taking action to seize control of the country. Meanwhile, with only the memories of the Devil’s Scientist, Katsuragi Takumi, Kamen Rider Build aka Kiryuu Sento grows desperate to find a way to defeat Evolt.
Utsumi: It’s good to see you Katsuragi.
Takumi: You’re… Cyborg Utsumi.
Utsumi: So you were calling me that behind my back, too… That’s a mild shock. But even I’m a Kamen Rider, now.
Takumi: So you did want to become a cyborg.
Utsumi: I’m not responsible for what happens if you keep mocking me. Now watch episode 39!
Utsumi has forsaken Earth's survival following the death of his master Juzaburo Nanba, but is there anything that the protagonists can do now that he has acquired the power of the Evol Driver too as Kamen Rider Mad Rogue?
Episode Tropes:
- Big Damn Heroes: Kazumi shows up in the nick of time to save Gentoku from being killed by Utsumi with a Castle Discharge Crash and borrows Gentoku’s Nebulasteam Gun to help everyone escape from Evolt and Utsumi.
- Borrowed Catchphrase: A weird example in that Takumi himself uses the self-gloating genius lines, and Misora mutters to herself that Sento apparently retained it even after losing his memories as Takumi.
- Butt-Monkey: Ryuga gets compared to a monkey a few times in this episode, and even early on, Misora and Kazumi bluntly agree with Takumi saying that Ryuga's thoughts make monkeys look advanced.
- Call-Back: The episode's title calls back to Episode 21: "The Unstoppable Hazard". In that episode, Sento started questioning whether he could call himself a hero after he killed someone under the influence of the Hazard Trigger. In this episode, it's Ryuga affirming that Sento is a hero that allows Sento to re-emerge from Takumi's mind and successfully use the Genius Bottle.
- Cue the Sun: A shot of the sun coming out from behind a cloud is shown as Sento returns.
- Dark Reprise: Utsumi demonstrates as Mad Rogue stronger versions of Gentoku’s two finishers from when Gentoku was Night Rogue.
- Don't Think, Feel: When Takumi questions why he couldn’t activate the Genius Bottle, Ryuga steps in to save him from being killed by a KaizokuHassyar finish and tells Takumi he’s overthinking his desire to protect.
- He's Back!: Sento returns after being on the sidelines for three episodes.
- It's All My Fault: Gentoku clearly feels guilty about using Utsumi and the past, and believes that had he not shot at Utsumi in Episode 12, the latter would not have turned against humanity.
- The Power of Friendship: When Misora suggests trusting Ryuga to not turn into another Evolt, Takumi rejects this trope after mockingly asking if their life was a shonen manga.
- Redemption Rejection: When Gentoku early on questions Utsumi on his sudden betrayal, Utsumi responds that he simply does not care. When Utsumi later by himself reflects on if he was wrong, he briefly considers the idea, but then rejects it completely, saying that he was not wrong.
- Something Only They Would Say: After Sento returns to being the dominant personality, he playfully laments that the "sub-characters" (mainly Ryuga) can't do anything without him. This immediately clues everyone in that He's Back!.
- Split-Personality Merge: After being spurred on by the feelings of Ryuga and Gentoku, Sento’s personality re-emerges from the depths of Takumi’s mind, and Takumi allows the Sento personality to take control of their body once more, with the mental imagery showing the two of them overlaid into one being.
- Talking Is a Free Action: Averted. Utsumi hits Takumi with a KaizokuHassyar finish while giving him a Hannibal Lecture on how science is how they express their power and dominance over others.
- This Is Reality: Katsuragi dismisses the heroes' belief in The Power of Friendship as nonsense straight out of a shōnen manga.
- Took a Level in Badass: Takumi shows that in addition to his newly created Genius Bottle, he had fine tuned RabbitRabbit so that it was better for him to wield. Even so, the fact that he created the Genius Bottle didn't help him when he tried to activate it and it failed to respond.
