Our heroine, Airi, is a girl with a modest bust. One day, she discovers a suspicious creature named "Iso-kun" deep in the pool's pump room, and is intrigued by its "typical tentacles." Unable to contain her sexual curiosity, she lifts up her swimsuit and lets it crawl over her. It's gross, but it feels good! Airi is so taken with the creature that she goes deeper into the pump room again, only to have her virginity taken this time. How tragic... What will Airi's fate be?