Hissatsu Chikan Nin - Season 1

Based on the game by Anim. During her daily train ride, a young woman observes a man sexually assaulting a female passenger. She intervenes not by confronting the assailant or seeking aid, but by engaging in self-stimulation while watching. This act draws her into the molester's orbit, where she transitions from a spectator to a compliant participant. She eventually assists him by enticing her attractive friends into similar situations, actively recruiting new victims for his schemes.