Mei, a younger sister, is tormented by the sound of adult videos coming from her older brother's room. One day, she reunites with her childhood friend, Mamoru. Mamoru is Kokoro to the way Mei has grown into a more mature woman. The sound of adult videos coming from her brother's room next door brings the two closer together. Frustrated by the sound of her brother watching adult videos, Mei feels intense pleasure during her first sex with her childhood friend...