Ao no hono-o

Shuichi Kushimori is a 17-year-old student who lives a happy life with his mother and his sister. Without warning, one day his missing stepfather, Sone, is back after a long absence. Sone is soon in a vicious circle of drinking and starts to harass his ex-wife and stepdaughter. When he makes sexual advances towards Shuichis sister, Shuichi decides to take matters into their own hands.After careful and precise preparation Shuichi puts his plan into action. It seems that he has committed the perfect crime, autopsy reveals a natural death and Shichi cleared of all suspicion. But the murder weapon disappears from the hiding place and soon the young killer is filled with doubt, fear and anxiety. - IMDb