A seasoned detective is called in to rescue a politician held hostage by a lunatic. In a brief moment of uncertainty, he misses the chance for action. Leaving his job and family without explanation, he makes his way to a mountain forest, encountering a peculiar tree called Charisma.

Takatoshi Minamiyama (Sota Fukushi) majors in art at an university in Kyoto. On the train to the school, he sees Emi Fukuju (Nana Komatsu) and falls in love with her at first sight. Gathering up all his courage, he speaks to her. They begin to date and enjoy happy days together, but Emi reveals her secret to him.

Based on the classic adult manga of the same title, this film depicts the love between a stepbrother and sister discovered one weekend when their parents go away. The relationship must come to an end, but not before it changes their lives forever.