A high school reunion trip with three old friends turns into a steamy two-day getaway at a hot spring. Among them, Yumemi, once a close male friend, has undergone an unexpected transformation—shedding his masculinity and emerging as a stunningly cute girl. Shocked and intrigued, the group finds themselves irresistibly drawn to her charm. Boundaries blur as friendships cross into forbidden territory, giving rise to intense, erotic connections. A mysterious journey unfolds, blending warmth, intimacy, and raw desire.