Reiko Makihara (46), a married woman, lives alone due to her husband's work transfer. She works as a fitness instructor from home and currently teaches two students: 40-year-old Miyazaki and 21-year-old Okumura. Reiko draws attention with her mature, sensual physique and stylish presence. While both students are drawn to her, Okumura is especially captivated by her movements and demeanor, developing a stronger attraction compared to the more serious and focused Miyazaki. Jealous of Reiko's gentle guidance toward Miyazaki, Okumura abruptly leaves early. That night, the remaining pair, Reiko and Miyazaki, fall into a strange, intimate atmosphere, and Reiko gives in to her hidden desires. A few days later, Okumura learns of their affair and desperately wants to become part of their world, setting the stage for a new development.