Yuna Ishikawa, a married young woman, seeks her first lesbian experience by attending a free trial session at a newly opened private gym nearby. However, unable to endure the lewd instruction from the female trainer Yuri, she tries to flee the scene. But Yuri follows her to her home, pins her down on the bed, and overwhelms her with intense lesbian kissing and nipple play. Yuna's young, sensitive body reacts violently as she succumbs to the relentless stimulation. Through Yuri's persistent advances, Yuna is drawn deep into a world of pleasure unique to women, experiencing a moment so intense it becomes unforgettable.