DSOD-099 POV: A busty childhood friend—plain-looking, bespectacled, and freckled—whispers, "Will you teach me about sex?" shattering your self-control and driving you to repeatedly creampie her in a frenzy of intense, lust-fueled arousal. Nanao Satsuki.

Takashi lives alone with his mother. One day, his childhood friend Nanao comes to visit. Concerned about her son's poor grades, Takashi's mother asks Nanao to tutor him. Although Nanao is a quiet, unassuming type, she possesses a strong sense of responsibility and a natural aptitude for leadership; she agrees to the request and begins tutoring Takashi. While diligently helping him study, she happens to discover an erotic magazine in his room. Intrigued and curious about sexual matters, Nanao suddenly declares that she wants to watch him masturbate...