Takumi Fujiwara finally joins Ryousuke and Keisuke Takahashi to form "Project D." Their objective is twofold: Ryousuke seeks to develop his "High-Speed Street Racing Theory," while Keisuke and Takumi aim to refine their driving skills by confronting powerful opponents on hazardous roads. The concept behind Project D is to challenge street racing teams from other prefectures in order to improve both their uphill and downhill records. To draw the attention of top racing teams, Ryousuke establishes a dedicated website to announce Project D's upcoming battles and publish the team's results. The fourth season of Initial D chronicles the struggles and triumphs of the Project D members as they strive to become the premier street racing team outside of Gunma Prefecture.