Five cases of murders are reported at the same time at different parts of the city, but each victim is killed in a different way. While Kyu leaves for home to search some clues regarding the case, Genpachiro remembers that a security camera captured a picture of the suspect and his bike which surprisingly reveals to be Chase. At the Drive Pit, Go decides to hunt him down on his own while Shinnosuke and Mr. Belt agree that Chase has to be killed. Shinnosuke decides to stick to Kiriko's ideals, but promises to kill him if Chase is truly the cause of the murders.
At a ship, Medic lies about Roidmude 072 and her Reapers' demise at the hands of Drive and decides to take matters seriously. After Chase fully heals, he receives a report that he is followed. After incapacitating Gen and his policeman accomplice, he traps them in a Heavy Acceleration wave. Shinnosuke and Kiriko rush to the scene as Mach appears and fights Mashin Chaser. Shinnosuke as well transforms into Drive, bringing Genpachiro and his accomplice to safety via Dimension Cab and fights Chaser. After Chaser traps Deadheat Mach in a Super Heavy Acceleration, he easily overpowers him until Drive Type Technic stops him and tries to reason with his actions for killing humans. Chaser however reveals that he only defends his own kind and thinks of nothing else, fearing Kiriko and Mr. Belt.
Medic orders Chaser to retreat and let her Reapers fight the Riders. She uses her Roidmude form combined with her ballet performances for her attacks. With her Reapers having joined the brawl, she modifies Roidmude 104's right hand into an arm cannon, which explains the creation of Reaper Legion Roidmudes while Brain watches from afar, now knowing her to be the reason behind Chase's increasing power. She orders her minions to retreat while leaving 104 to handle the rest. 104 uses his newfound weapon in an aerial fight until he is destroyed by Mach's Beat Macher Full Throttle.
At the Unit's office, Genpachiro has revealed the Riders' true appearances and deduces the green and black ones as two other unnamed Riders until he is corrected. Remembering previous cases, Shinnosuke reviews the victims as templates for previous Roidmudes used as human disguises, having spoted one from the picture as Roidmude 037's human form, meaning that the original ones were disposed so that Roidmudes could took their places. Kyu quickly arrived and revealed that Roidmudes can travel through computers using their Cores and 072 from prior went into Kyu's blog. Kyu used his method to track Roidmudes via computer network. Mr. Belt sends the Shift Cars to gather the relation without knowing that all of them have been captured by Medic.
Brain meets Chase in his room and gives him "something" to help Chase in his later confrontation against Drive. While Shinnosuke and Kiriko are patrolling in Tridoron, they pick up Justice Hunter's SOS sign. Mach tails Chase on his bike, but is quickly interrupted by Medic, who has Heart take care for Mach. They arrive at Hunter's spot but the Shift Car attacks Shinnosuke and leads him to Chase, where all 18 known Tire Exchange Shift Cars had been placed under Medic's control. It was revealed that all those murders were nothing but baits as she staged Drive's defeat by stripping him of his subordinates, while Mach is confronted by Heart.
Before the slow-motioned Kiriko and Shinnosuke are about to be killed, Shift Wild and Technic quickly docked themselves into their Shift Car Holders to save their lives. Shinnosuke as Drive Type Wild tries to fight, but is overpowered by the improved Mashin Chaser as well as the enslaved Shift Cars. In the end, Mashin Chaser traps him in a Super Heavy Acceleration, slowing Drive's movements greatly and having the advantage. Mach decides to risk his own safety by delivering Shift Dead Heat to Drive but even as Type Dead Heat, the Super Heavy Acceleration reduces his high combat capabilities.
Drive tries to remind Chaser of his old life as Protodrive which succeeds, but he regains his sense and assumes Triple Tune. Mr. Belt is forced to reveal another secret: he had stored a Type Change Shift Car, but was forced to hide its existence due to the danger it carried. Nonetheless, Drive allows for the Shift Car's arrival, having no longer begrudging Mr. Belt for keeping secrets. The Triple Tune Mashin Chaser deliberates Drive with his attack by using the enslaved Shift Cars to ram into him. However, a strange new Shift Car enters the blaze and gives Drive a new form: Type Formula.
- Apparently Unrelated Murders: Outside of happening at the same time, the victims have nothing in common, down to the way they were killed. Then it turns out that they were templates for several past Roidmudes that the Riders already dealt with.
- Brainwashed and Crazy: All of the Tire Koukan Shift Cars are brainwashed via Medic to attack Drive and work for Chase.
- Curbstomp Battle: With his new upgrades, courtesy of Medic, Mashin Chaser completely trashes both Drive and Mach, even in Deadheat. Further more without Deadheat, Mach doesn't stand much of a chance against Heart.
- Darkest Hour: Shinnosuke first had to fight against Chase along with [the Shift Cars thanks to Medic and is caught by Chase's Super Heavy Accleeration before getting thrashed while being frozen. Gou meanwhile fights against Heart thanks to Medic's intervention and he decides to throw Deadheat back to Shinnosuke to help him even if it meant the fight between him and Heart becomes one-sided. However even in Deadheat, Drive still feels sluggish from Chase's power and gets pummeled. It's gotten so bad to the point that Belt decides to summon a Shift Car he kept hidden from Shinnosuke to use and it is even harder to use than Deadheat.
- Death of a Thousand Cuts: Chase does this on a random tire after getting an upgrade from Medic.
- Ground Punch: How Mashin Chaser activates Super Slowdown.
- Hope Spot: Kyu figuring out how to track Roidmudes without depending on detecting Density Shift. It's a major accomplishment for the Special Unit, but Medic's plan rendered it moot.
- "I Know You Are in There Somewhere" Fight: Shinnosuke tries this again on Chase, but it ultimately doesn't work.
- Oh, Crap!: Both Gou and Shinnosuke when Chase activates his Super Heavy Acceleration.
- Serial Killings, Specific Target: The victims were killed in order to lure out Drive.
- The Roidmude Count: 75The Answer: Medic's ultimate plan against the Riders.
