Set in a futuristic Japan where crime has elevated and apathy prevails, Tsukasa is brought up as a boy in order to protect her from the crime-ridden Japan. When the murder of Tsukasa's parents leaves her and her brothers homeless, she finds herself turning to the same people responsible for the deaths of her parents - the yakuza and fellow classmate/Yakuzi head, Ryuji. From their very first meeting, Tsukasa finds herself in debt to Ryuji, and the only way to pay it off is to become his bodyguard. Yet, the incurring debt seems to greatly increase, regardless of how much Tsukasa works. Perhaps Ryuji has other reasons for keeping her by his side?

伝説の聖妻「若桜」の娘としての運命に思い悩む司。そんな彼女をよそに、竜二率いる九竜組は牙流会との全面戦争に突入!!　だが深角の狙いは司にあった─!?

牙流会分裂の混乱の中、身体と兵器を融合させた最終兵器\[バケモノ\]に襲われる司と竜二たち。捕われた朝来を助けるため、銃もきかぬ超人的な敵相手に司は—!? そして、竜二をかばった鴨島が重傷を負い…!!