Following their narrow victory against Purple Shadow, Project D's reputation is at stake after a pair of imposters parade around Saitama. Initially Takumi seems oblivious to the incident, but takes notice after he is mistakenly blamed for taking advantage of a girl. Meanwhile, the final stage of Project D's expeditions is upon them, and is to be the hardest yet.

Keisuke's next opponent in Kanagawa's Four Lines of Defense is the leader of Team Spiral, Ryuji "Zero" Ikeda. Ikeda believes in his "Zero Theory", where the driver thinks of nothing except being one with the car to create the ultimate racer. Quite similar to Ryosuke's Fastest Racer Theory, Ryosuke also notices a few flaws in Ikeda's theory. A flaw that would arise as the wet conditions create a fog battle.

Takumi and Shinji continue with their match with Takumi, still bewildered by Shinji, starts to focus. But suddenly, Shinji allows Takumi to pass, which disturbs Takumi even more. Even Kubo is utterly disheartened by the turn of events, but both Go and Ryosuke believe this was inevitable, creating a suitable conclusion to Project D's expeditions.

The intense downhill battle between the two drivers are reaching an end, as Takumi and Shinji race to their absolute limits. As this battle comes to a close, and the reign of Project D finally ends, the true meaning behind the "D" will be revealed. As the characters go on different paths, Takumi's passion to be "the fastest one out there" will never end.