1995. Kazama, who runs the Sunflower orphanage, had hoped that Kiryu, Nishiki, Yumi, and Miho would lead honest lives. However, contrary to his wishes, the four are ultimately plunged into the underworld of the yakuza. Meanwhile, in 2005, tensions between the Omi Alliance and the Tojo Clan are at a boiling point over a 10 billion yen heist.

1995. The Doujima Family closes in on Edgar's younger sister, who was entrusted with the official seal necessary for selling his land. Meanwhile, Yumi travels to Osaka in search of her estranged older sister. At the same time, the battle over Edgar's seal escalates. In 2005, Aiko disappears, leaving her daughter Haruka behind. Kiryu and Yumi decide to protect Haruka, but they soon make a discovery.

In 1995, an overworked Miho falls seriously ill. Nishiki, deeply concerned for his sister, finds himself at the mercy of Doujima's scheme that exploits his vulnerability. In 2005, while Kiryu and Yumi continue their search for Aiko in Osaka, they encounter Chairman Goda of the Omi Alliance, who forces them to promise to return the 10 billion yen by midnight the next day.

In 2005, Kazama meets with Chairman Goda of the Omi Alliance in an effort to prevent a war with the Tojo Clan. The unresolved conflict between Kiryu and Nishiki from ten years ago resurfaces, once again driving a wedge between them. In 1995, Kiryu, who had been on a winning streak in underground fighting to fund Miho's surgery, finally reaches the pinnacle with a high-stakes title fight.

1995. The bond between Kiryu, Nishiki, Yumi, and Miho, who had been there for each other like family, tragically falls apart. 2005. Can Kiryu prevent a war between the Tojo Clan and the Omi Alliance? How will Kiryu and Nishiki resolve their 10-year-old conflict? And what is the true identity of the Shinjuku Devil? With rising tensions, they face the final battle in Kamurocho.