Misa is a woman in her mid-twenties working as a teacher. She married a colleague and gave birth to a son named Koujirou. However, due to prolonged marital discord, she decided to divorce by the time Koujirou reached middle school. As a result, Koujirou grew up without a father and naturally developed an interest in becoming a teacher, eventually choosing that career path. One day, Misa plans a trip with Koujirou and her ex-husband for the first time in years. However, just before departure, her ex-husband cancels due to sudden work commitments, causing the plan to fall apart. Deciding not to waste the opportunity, Misa sets out on the journey with Koujirou alone. During this trip, their relationship takes a new and intimate turn.