Momoko, proud of her academically gifted son, Kosuke, who didn't resemble her. However, that pride was shattered by a letter revealing he was switched at birth. Despite her sorrow, she gradually accepts the confusion of secretly viewing him as a man. Kosuke, upon learning the truth, confesses his own struggle with realizing he'd been subconsciously attracted to his mother as a woman. And so, amidst the rain, they find themselves drenched and passionately seeking each other out...