Toujou Natsu has the face of a student but her figure is better than that of a woman. Her perverted stepfather was attracted to her body. On the occasion of Toujou Natsu's mother returning home for three days, he took advantage of her while she was sleeping to molest and possess her and force her to serve him over and over again.
And during these three days, She can't go to school, work part-time, or even leave the house. She should have felt disgusted by his actions but no! She felt excited, happy and happy again when her stepfather brought pleasures that she had never experienced before.