Ko Sho was ten years old when his father died in a traffic accident. Since then, Chisato Shoda has worked tirelessly, raising her son alone. Having watched her dedication for years, Ko gradually began to see her not just as a mother, but as a romantic partner. One day, Chisato's company, concerned about her overwork, forced her to take paid leave and automatically booked a stay at an affiliated hot spring inn. Hesitant to go alone, Chisato invited Ko to join her on the trip. At the resort, Ko finally confesses his feelings to her. But Chisato struggles—she is still his mother, and accepting him as a lover feels premature. Amidst this emotional conflict, how will their relationship evolve?