After moving to the city to attend university, Ryuichi temporarily stays at his aunt Shihori's place. Reuniting after a long time, she warmly welcomes him and cares for him with genuine affection. However, Shihori's husband has left home due to debt, leaving her to struggle on her own. One day, Ryuichi accidentally sees his aunt in the bathroom and feels his heart race. Her deep red, alluring nipples sway with her movements, exuding the sensual charm of a mature woman, stirring something deep within the young man. In that moment, a new emotion begins to awaken inside him.