"Rika" and "Ruka" are fraternal twins who love their older brother and always compete for his attention. One day, "Ruka" peeks at her brother while he is taking a bath and catches him masturbating with lotion. Seizing the opportunity, she uses her swimsuit, lotion, and large breasts to seduce her brother and extract his semen. Seeing this scene, "Rika" starts to seduce her brother in order to win him back.
