Description：Second-year junior high school student Hideichi Kushimori (Kazuya Ninomiya) lives with his mother Tomoko (Kumiko Akiyoshi) and sister Haruka (Anne Suzuki). Hideichi's father died in a car accident a long time ago, and his mother remarried Sone Takashi (Kansai Yamamoto) ten years ago, but this marriage ended prematurely because of Sone's violent tendencies. One day, Sone returned to the Kushimori family. Hideichi discovered that his mother seemed to have some hidden worries and was unwilling to drive Sone out of the house. On the other hand, Sone seemed to have bad intentions towards Haruka. Hideichi, who was resentful of his stepfather, had no choice but to buy potassium carbonate online and decided to kill Sone. His plan was successfully implemented, but he himself fell deeper and deeper... This film is adapted from the novel of the same name by Yusuke Kishi.