Can you do it so that I can feel my nipples too? After witnessing her brother masturbating, Yayoi helps him with playing with his nipples. At first, Yayoi is confused by the act itself, but as she begins to feel happy seeing her brother writhing in agony and his expression, she quickly becomes more skilled at playing with his nipples, perhaps because of her desire to be more useful. ... A forbidden nipple play that brings out her wicked maternal instinct as a woman.