Ruri is left to look after her friend's child while her friend and his wife are away on a trip. She discovers a pink vibrator that seems to belong to her friend. Unable to suppress her desire due to the excitement and sense of guilt of having seen something she shouldn't, Ruri places it between her legs. Then the child, who was peeking at the whole thing... Aroused by the lewd appearance of a woman he has never seen before, the boy goes on a rampage and begs Ruri to teach him.