The Hazuki family’s maid, Ine, delivers a letter to Ryo, who is uneasy about his father’s death. The letter was sent by a person named “Yuanda Zhu” to his father, containing characters he cannot read. Ryo begins to investigate the letter to find out about his father’s past. As he investigates, he is targeted by the “Mad Angels”, the gang that runs the underground business of Yokosuka Harbour.