As his father's work became increasingly busy, Masashi began spending more time at his aunt Shizuka's house. Captivated by her big, soft breasts—so different from his mother's—he started pursuing Shizuka, ignoring even his cousin Nobuya. Eventually, Shizuka let her guard down around Masashi, leading to a physical relationship between them. But as Shizuka awakens to her own desires, a new change stirs within her heart.