Ataru had discovered his stepmother Yuria's hidden secret. Though she always remained fully clothed, she was secretly masturbating. Yuria was young, with a voluptuous bust, exuding erotic charm even through her clothes. Ataru found himself captivated by her, his heart stirred daily. One day, Ataru was asked to help clean the bathroom after his stepmother's bath. At that moment, shower water soaked Yuria's clothes, leaving her completely see-through and exposed before his eyes. Unable to resist, Ataru was overwhelmed by uncontrollable desire.