Shinnosuke, Kiriko, and Go are on their way to Kyu's autograph session when a Heavy Acceleration wave was released and a giant television screen on a building exploded. Go quickly transformed into Mach and rushed to the scene. As Roidmude 072 was about to drop a female victim from a height, Mach and Drive appear, causing him to feel amazed as he had finally seen the two Kamen Riders. Drive notes that he sounds familiar. However, he ran away after two half-evolved cockroach-like Roidmudes attacked him and overpowered the Riders.
Mr. Belt gets Kiriko and the Shift Cars to track 072, only to end up at Kyu's apartment. Shinnosuke and Go arrive there as well, and the three hear what seems to be Kyu arguing with himself. They barge inside to find two Kyu Saijos inside, and arrests them both. Meanwhile, Medic introduces Heart to her Reaper Legion Roidmudes that were tasked to carry out Chase's former duty as a Grim Reaper as Brain gets jealous of her overwhelming success.
At the Special Investigation Unit office, both Kyus were distinguished by wearing different colored shirts, one known as Black-Saijo, and the other, White-Saijo. Black-Saijo tries to lie that both of them are twin brothers, but none of the other unit members fall for it. They end up being interrogated at separate rooms. White-Saijo tells Kiriko and Shinnosuke that he met Roidmude 072 on New Years' Eve. As he was unable to kill Kyu, the two stayed together, with 072 taking over Kyu's place in the Unit at times, trying to gather information about the Kamen Rider.
As both Kyus exit the Kuruma Driving Office, Gen threatens to force a confession out of them with a fake rifle but fails. Shinnosuke arrives and brings out a limited edition of a commemorative plate (a replica made by Shift Cars Colorful Commercial and Spin Mixer) of the anime Murmur Mansion. He throws it into the air, and both Kyus rush towards it. White-Saijo catches the plate, exposing his true identity as Roidmude 072, as the real Kyu is less athletic. Shinnosuke figures that Kyu was not coerced into living with 072, he chose to live with 072 on his own accord. The real Kyu reveals that before 072 was about to kill him, Kyu requested that 072 let him watch the final episode of his favourite anime before his death. Both Kyu and 072 watched the anime, and were touched by it. Ever since then, Kyu and 072 lived together.
At the day of Kyu's autograph session, 072 went to the press conference for the movie edition of Kyu's favourite anime, Murmur Mansion. However, once he hears that the movie will be dubbed over by voice actors and actresses, one of them being the victim from earlier in the episode, he went berserk and released the Heavy Acceleration wave, and went on to punish the voice actress, as the anime is better with subtitles and using voice actors would ruin the anime. Shinnosuke sees 072 as a good guy, affirming his belief that Roidmudes and humans can coexist in harmony. Kiriko is reminded of Chase after hearing this. As 072 tells his wish of continuing to stay with Kyu, he is killed by Medic. As he dies, 072 instructs Shinnosuke to lie to Kyu that 072 went berserk and was defeated by the Kamen Rider, in order not to affect Kyu emotionally too much.
While Go as Mach attacks the Reaper Legion, Medic claims herself and the others as the new Reapers and says that no matter how many times they reset rogue Roidmudes, those Roidmudes would get out of the line again. To solve this, she and her Reapers secretly eliminate their Cores. Drive objects to her explanation and labels her a demon compared to Chase, the former Reaper, who gave rogue Roidmudes a chance to live again by retaining their Cores, and assumes Type Dead Heat to attack her. After assuming Type Dead Heat Flare, he initiates a Dead Heat Drop while Medic uses her Reapers to cover her escape. Drive screams loudly in anger after the battle.
Kyu was deeply affected by his loss after Shinnosuke told him the lie but still, Jun comforted him. Shinnosuke quickly ran away while Kiriko was forced to help Jun filling in his reports.
Standing at a ship, Medic is disgusted at Drive for being able to lay an injury on her. She transforms into her Advanced form.
- Burning with Anger: Played with. After Medic remorselessly kills 072, a very angry Shinnosuke transforms into Type Dead Heat and on top of that he Tire Changes into Max Flare.
- Department of Redundancy Department: Averted. Using Max Flare in Type Dead Heat is to exemplify an even higher level of Shinnosuke Burning with Anger.
- Fake Twin Gambit: Kyu and the Roidmude have been pulling this off, finally getting busted in this episode.
- Impaled with Extreme Prejudice: The fatal fate for 072.
- Mood Whiplash: The first half of the episode is comedic and even heartwarming... but then Medic shows up.
- Mundane Utility: Our heroes cook up a fake limited edition collectible by having Spin Mixer and Colorful Commercial carry out 3D printing.
- Roaring Rampage of Revenge: Oh boy, did Shinnosuke go ballistic! Needless to say, Medic's days are numbered, if Shinnosuke has any say in it.
- Show Within a Show: Murmur Mansion. Turns out Kyu's Creepy Doll collection is the merchandise!
- Spot the Impostor: The Special Unit has to figure out which Kyu is a Roidmude.
- Bluff the Impostor: After several failed attempts at this, Shinnosuke copies a limited collectors item and throws it in the air. The real Kyu trips trying to catch it, but the Roidmude catches it with it's exceptional agility.
- Subbing Versus Dubbing: Serves as an In-Universe plot point: The reason why 072 attacked the idol? Because she was going to do the voice over in the movie adaptation of the silent anime series Murmur Mansion.
- When 072 says Shinnosuke wouldn't understand his motives since he doesn't watch Murmur Mansion or anime in general. The detective then marathons the entire series and realizes what's going on. He comes to agree with both Kyu and the Roidmude that dubbing Murmur Mansion is a terrible idea and that it needs to be watched subtitled in order to get the most out of it, and 072 simply wanted to lecture the actress on this.
- Wham Episode: It's the first episode to have a Roidmude directly kill another Roidmude, the first time we see Shinnosuke get Kouta levels of angry, and we find out that Medic is planning to cull the Roidmudes to a select few. On top of this, it's the first episode where to have its case closed in a single episode.
- The Roidmude Count: 76The Answer: Since New Years.
