Kanna and Konatsu became step-sisters after their parents remarried, but since their parents are away on honeymoon, they are living alone together for a while. While living with her step-sister, Kanna can't suppress her lesbian side and gradually starts to play with Konatsu's sensitive body... Her obsessive nipple stalker sister-in-law teases her and relentlessly stimulates her undeveloped pink nipples, eventually developing a sensitive premature ejaculation constitution where she can only cum from her nipples.