Yuri comes to visit from out of town and is introduced as his mother's longtime best friend. Her beauty and enormous breasts instantly captivate the adult son, who had planned to retreat to his room after a quick greeting. Having barely interacted with women besides his mother, he wants to get closer to Yuri but can only blush, fall silent, and avoid her gaze. Amused by his innocent reaction, Yuri offers to teach him about a woman's body.