After earning a series of difficult victories in the prefectures of Tochigi, Saitama, and Ibaraki, the drivers of Project D—an amateur street driving group led by ex-street driver and expert tactician Ryousuke Takahashi—Takumi Fujiwara and Keisuke Takahashi now have to take Project D to the next level: the Kanagawa prefecture, commonly known as the holy land of street racing. Their opponents, members of the three best street racing teams of Kanagawa, design an elaborate strategy called the "Four Lines of Defense" to put a definitive end to the ambitions of Project D.

Meanwhile, Takumi feels he needs to refine his driving skills to overcome the last victory against Toshiya Joushima that he only just managed to snatch. The moment of truth has now come for Project D, which carries with it the hopes of the Gunma Prefecture; will they manage to thwart the surprising tactics of the skilled street racers of Kanagawa?