Hazuki Family's maid Ine hands a letter to Ryo, who is restless from his Father's death. The letter was sent from a person named "Yuanda Zhu" to his father which contained characters he cannot read. Ryo begins investigating the letter to find out his Father's past. As he further investigates, he is targeted by "Mad Angels", the gang that runs Yokosuka Harbor's underground business.
And, to be frank, I don't even know
if these are things that a son should know.
.وبصراحة، لا أعلم إن كانت هذه أمورا يجدر بالابن معرفتها
Und ich weiß nicht, ob es etwas ist,
was ein Sohn wissen sollte.
E, para ser franco, nem sei se são 
coisas que um filho deve saber.