A boy by the name of Itsuki Sato had witnessed his mother die when he was at the age of five. Itsuki Sato’s mother had died because she had seen this man kill another man. The man who killed that other man killed Itsuki Sato’s mother since she saw him kill that man. Itsuki Sato was traumatized when he saw his mother get killed. The man walked up to Itsuki Sato and told him to try to get revenge on him when he’s older. 17 years pass and Itsuki Sato had not forgotten on what happened that day. Itsuki Sato was ready to make sure his revenge was fulfilled.