An 18-year-old beautiful girl named Momo, pure, innocent, and radiating transparency. Through the "Doki Doki Spread Open" series, presented in an almost entirely POV format, she calls out for her big brother while taking on various challenges. At first trembling with nervous excitement, her breathing gradually grows heavier, until finally, a visible wet spot forms on her panties. The charm of this work lies in Momo's genuine emotions and the subtle, evolving intensity of her feelings.