-->'''Shotaro''': "Danger is always by my side. That's a detective's fate."
-->'''Kirihiko''': "Strong feeling like anger or hatred can change a human's body or mind into a Dopant!!"

!!Titles:

* The V stands for "Virus" and "Vehicle".
* Part 1 is subtitled "Infected Car".
* Part 2 is subtitled "Grudge Beast".

At the Narumi Detective Agency, Akiko has fallen ill with a cold and calls Shotaro an "idiot who never catches a cold", spurning Philip's interest in this phrase despite not knowing that it is an idiom. The agency then gets a phone call from a man named Mikio Aoki who claims that he is being chased and needs help. When Shotaro arrives on the scene, he comes across the man before seeing a black SUV run through him, causing the man to writhe in pain before falling down dead. When Shotaro is taken in for questioning at the police station the next day, Makura thinking that he murdered Aoki, Jinno arrives to reveal that Aoki died from a mysterious disease.

Deciding to get to the bottom of it, Shotaro learns from Watcherman that Aoki was a member in a chop shop street gang. They head to the gang's usual hangout to talk to its leader Kurosu. Shotaro questions him, until Kurosu pulls a gun on Shotaro after one member of his posse hints that the SUV was stolen. Akiko, scared for their lives, drags Shotaro out before the other two gang members leave and talk about checking out the SUV. Shotaro trails them as the SUV appears once more to run down the other two members, killing one of them before chasing after the other. Shotaro contacts Philip to transform as Philip is still investigating the idiom. Shotaro instead activates the Bat Shot to take photos of the driver, eventually transforming into Kamen Rider Double to save the younger gang member before the Nasca Dopant intervenes. This allows the SUV to run down the gang member.

Later, Philip identifies the driver as Kōhei Yamamura, whose older sister Sachi Yamamura was hit by a car driven by Kurosu's gang and is currently in the hospital in a coma. Believing that Kōhei is the Dopant, Shotaro confronts him and accuses him of it. Kōhei runs off into a bus to escape to continue his revenge, succeeding because Sachi's fiance Noriyuki Yushima just got off the bus and holds Shotaro at bay. After talking to Yushima and learning about Kōhei, Shotaro gets a call from Akiko that she has followed Kurosu to a warehouse so he can gun down Kōhei in the SUV. Kamen Rider Double arrives at the warehouse on the [=HardBoilder=], provoking Kōhei to chase after him. Assuming [=HeatMetal=] and using the [=RevolGarry=], Double manages to wreck the SUV without being infected. While inspecting the wreckage with Akiko, they find no trace of a Gaia Memory...because the real Virus Dopant appears.

The Virus Dopant kills Kurosu as Kamen Rider Double is powerless to keep the monster from running away as Shotaro senses sadness from it. The next day, after reviewing how the hit-and-run on Sachi began the Virus Dopant's attack, Shotaro believes that Yushima is actually the Dopant. Heading to a girl school where Yushima teaches art, Shotaro finds the Virus Dopant attacking Yushima. Double saves Yushima and fights the Dopant before it runs away.

Back to square one, Akiko believes that Sachi may be the guilty party. Though Shotaro could not believe it, Akiko and Philip visit the hospital where Sachi is being kept and he finds her Living Connector. Philip concludes that the Virus Dopant is formed from Sachi's consciousness, and seeks to contact her through the Gaia Library. Upon meeting her, she tells Philip that just before she received the Virus Memory, she caught Yushima proposing to another woman.

Elsewhere, Shotaro learns from Queen and Elizabeth that Yushima is a casanova who uses women for his art. When Shotaro goes to confront him, he arrives just as the Virus Dopant is about to kill Yushima. Shotaro begs the monster to stop while he forces Yushima to apologize to Sachi. Neither Shotaro nor Philip can reason with Sachi, leading the powers of the Virus Dopant to take over, forcing them to transform into Kamen Rider Double to fight the Virus Dopant.

After Philip realizes that the only way to defeat the Dopant is to completely destroy its manifestation, Shotaro decides that they transform into [=HeatTrigger=] and use the Trigger Explosion Maximum Drive to deal the deathblow. The Virus Dopant is vaporized and the Virus Memory is ejected from Sachi's body and breaks. Soon after, Shotaro punches Yushima for causing the deaths of the four gang members by breaking Sachi's heart.

A few days later while closing the case, Shotaro begins showing symptoms of a cold.

!!Tropes:

* AssholeVictim: The gang members involved in running Sachi over all die. Philip and Akiko even question if they really deserve Shotaro's efforts to save them.
* BitchInSheepsClothing: Yushima initially appears to be Sachi's fiancé, an artist who has difficulty selling his art and a potential user of the Virus Memory. Things look good when Kōhei asks him to delay Shotaro, and Yushima does so without asking why. Things look ''less'' good when the Virus Dopant, who had only been taking revenge on the gang members, suddenly starts focusing on him. Then it turns out that not only is he guilty of running a ModelScam on multiple women, but a ''marriage'' scam as well, and Sachi even purchasing the Virus Memory was due to her catching him proposing to another woman. He even throws his newest fiancé in the way of the Virus Dopant to try and get away from her. By the end of episode 12 there's very little sympathetic about him.
* BittersweetEnding: Sachi is still in the coma by the end of the episode and Yushima [[KarmaHoudini gets away with nothing more than a punch in the face from Shotaro]], but Shotaro also manages to stop her from completely losing herself to rage and despair, and her younger brother is recovering nicely. And the gangsters that ran Sachi over end up dead, so not everyone gets off scot free.
* BrickJoke: Shotaro keeps crossing paths with things that protect from colds, but keeps foregoing them. By the end, he starts sneezing.
* ClearMyName: Shotaro is initially implicated as the autopsy of the first death reveals no injury from the car crash. Nobody but Makura thinks Shotaro did it though, and the incident is dropped soon after.
* DirtyCoward: Yushima is quick to run away screaming from Sachi in her Virus Dopant form, even tossing away a girl he had been romancing in the hopes of escaping.
* TheDogWasTheMastermind: The culprit behind the serial murders being carried out turns out to be the comatose woman we see get run over at the very start.
* DramaPreservingHandicap: Saeko explains that the Virus Dopant ''should'' have the power to infect the entire city. The fact that it formed from emotions instead of a physical body means that its strength is down to a level Double can manage.
* HeyYou: Shotaro pulls this off on Yushima before asking the latter to "[[CatchPhrase count his sins]]", before punching him in the face.
* KarmaHoudini: No arrests are made, and Yushima even gets away with his life. Although Shotaro does deck him one to the face on Sachi's behalf. That said, the gang members do die for running Sachi over, so not everyone got away freely.
* KarmicDeath: The Virus Dopant used the ''very same car that ran her down'' on the gangsters.
* ModelScam: Queen and Elizabeth claim that Yushima has used his art-teaching job to run this scam, though [[NothingIsScarier they don't go into details]]. Worse, he apparently had recently gotten into doing a ''marriage'' scam, [[TruthInTelevision which is a real thing in Japan]].
* OffscreenTeleportation: By virtue of being disconnected from her body, Sachi's Virus Dopant form is able to pretty much teleport as it likes, though it crosses over with VillainTeleportation by way of how it teleports ''on''screen as well.
* RedHerring: Sachi's younger brother and Yushima are both speculated to be possible candidates for being behind the murders, as both have clear motives and the former is seen inside the car as it attacks the victims. They aren't, however, and Yushima is in fact the final target of the true culprit.
* RoaringRampageOfRevenge: Sachi and her brother are enacting one on the gangsters responsible for her hit-and-run. Unusually for this trope, when Philip talks to her via [[MentalWorld the Gaia Library]], Sachi states she appreciates why they're trying to get her to stop her revenge, but proclaims that her hatred for Yushima and the gangsters is all that's left in her mind right now.
* StringyHairedGhostGirl: Sachi's form as she appears via [[MentalWorld the Gaia Library]], which really isn't helped by the way that she clearly has ''blood'' on her dress and her missing one shoe gives her an hobbling step. She honestly looks like she's been run over...and she found the strength to ''stand back up''.
* SuperpowerLottery: The fluke of using the Virus Memory before entering a near-death state actually altered its properties, allowing the Virus Dopant to act independently of the host's body. Though interesting, it also reduces the power of the resulting Dopant to the point of ClippedWingAngel.
* TragicVillain: Sachi. Despite committing no less than four murders and nearly committing a fifth, she is ultimately just the broken mind of an emotionally scarred woman taken vengeance on the men who harmed her. The Virus Dopant's defeat is noticeably set to no music, demonstrating how her defeat is less a heroic victory and more a MercyKill.
* VanInBlack: A variation, in that the SUV ''is'' the antagonist for a while.
* WhatHappenedToTheMouse: Sachi had caught Yushima proposing to another woman before their own marriage was set to happen. After the first attack on him Yushima attempted to hide out at the second woman's home, and when the Virus Dopant attacked them there he pushed her into the Dopant's path. We don't see or hear if she is killed or not, but the last we see of her is her form on the ground and the Virus Dopant running after Yushima. Given how casually deadly the Dopant is, and Sachi's deteriorating mental state, it's not good odds that she's alive...
* WomanScorned: Sachi's Virus Dopant is effectively one, although it apparently took some of her brother's rage along with it. One shudders to think what would have happened if Sachi hadn't been run over, given the power of the Virus Memory and her hatred towards Yushima.
* WoobieDestroyerOfWorlds: Sachi ''reeeeally'' had it rough. In the end, Shotaro wasn't trying to save her victims as much as he was trying to save ''her''.
* YouHaveFailedMe: Kirihiko is about to pull this at the start of the episode on the memory salesman who sold the Virus Memory to Sachi. The strange thing is that it isn't for him selling a memory that could kill an entire ''city'' to a woman who just found out her fiance was a scam artist...but for it apparently being defective, a factory issue if nothing else.
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