Makoto was Kokoro by the lewd moans of his mother, Miki, coming from the bedroom. He was aware that his parents were planning to have another child, but he couldn't bring himself to support them. Instead of the joy of adding a new member to the family, he felt jealousy towards his father for making his mother make such lewd noises. And he felt possessiveness, not wanting to give his mother to anyone else. Every night he heard the sounds of his parents having sex, his twisted feelings grew stronger... And finally, Makoto carried out a forbidden plan. His plan was to fill Miki's vagina with his own sperm and expel his father's sperm.