The Naitō Shinjuku Family, Japan's oldest yakuza organization with a hereditary tradition, is led by its boss, Gunji Washio (Hitoshi Ozawa). His young son, Taiga (Haruto Ochiai), though only an elementary schooler, spends his days being trained as the heir by senior lieutenant assistant Reiji (Yoshiyuki Yamaguchi). However, in stark contrast to his father's wild and daring nature, Taiga is timid and prone to tears, raising doubts about his suitability as the next leader. Amid this uncertainty, Gunji's supposedly deceased younger brother resurfaces and assassinates him, plunging the Naitō Shinjuku Family into crisis. To make matters worse, Taiga is kidnapped by an unknown assailant…