A geeky college student starts living alone when he goes to college. Envious of him, his younger sister starts frequenting his room. One day, she runs into his friend. Like her brother, he is an introvert, so she seduces him by showing him her panties and enjoys his reaction. Having fun teasing the shy older man, the sister gradually escalates her actions, destroying her friendship with her brother. Awakened to her abnormal sexual desires, the younger sister drags her brother into her pursuit of psychological pleasure...