One day, Makino Haruka woke up feeling a strange sensation in her lower body. To her shock, a penis—something a woman shouldn't have—was growing there! Struggling to hide her panic, she suddenly sat upright with a look of realization. "Men touch this when they masturbate, right...? I wonder what it feels like..." she murmured, hesitantly reaching out her hand. In that instant, despite her astonishment at the physical change, a new curiosity began to stir within her. How will she come to terms with this mysterious condition? And how will she learn to accept and understand her transformed body?