"Rika" and "Ruka" are fraternal twins who love their older brother and always fight for him. One day, "Ruka" spied on her brother's bathing and witnessed her doing lotion masturbation. She took it upon herself to seduce her brother and exploit her brother's sperm using swimsuit, lotion and big boobs. "Rika" who witnessed the scene begins to seduce her brother to take it away.
