Koichi was disturbed by the screams of his mother, Yuri, leaking from his parents' bedroom. I knew my parents were making plans to have children. From the son's point of view, it may be something that should be celebrated. However, when he learned that Yuri had a lewd side that he had never touched, an uncontrollable emotion welled up inside him. It's jealousy of my father. And the monopoly desire to want to own all of the lilies. When that emotion reaches its limit, Kouichi's distorted affection for Yuri crosses the forbidden line.