Several years after losing his mother, Junya lived alone with his father. However, everything changed at the end of summer when his father returned home with Mayu, his new wife. For Junya, sharing daily life with Mayu—who felt too young to be called "mother"—became a confusing mix of unease and temptation. It was only natural for a boy entering adolescence to start seeing this suddenly appearing young stepmother as a woman. These conflicting emotions deepen the unfolding story.