Yuri Kudo's everyday life takes a dramatic turn when her son falls in love with her close friend, Yuri. Despite having never spoken to a woman before, he desperately tries to win Yuri's affection, but his efforts always backfire. Eventually at his wit's end, he devises a plan to at least keep a memory of her by using her underwear as a masturbation aid. However, his actions are accidentally discovered and he's caught red-handed by Yuri herself. In an unexpected turn, rather than getting angry, she gently kisses him, sending the story in an entirely new direction.