Yukiko Shimatani, a 39-year-old mother, heads to her son's room after a bath and encounters an unexpected scene. Her son is masturbating while holding an erotic magazine featuring married women. Flustered and embarrassed, the son tries to compose himself, but his eyes are drawn to his mother's towel-clad body, causing his groin to stir uncontrollably. Sensing his arousal, the mother gently touches her son's engorged penis, leading them both into uncharted territory.