This anime adaptation of a visual novel is a thrilling tale of survival from a lewd creature. The story revolves around a group of vacationers who find themselves stranded on a secluded island in the southern seas, accessible only by boat once a week. The island boasts a luxurious hotel, but their stay takes a dark turn when parasitic monsters with lewd tentacles unexpectedly appear, causing chaos and fear among the guests. As the terrifying situation unfolds, the vacationers are forced to confront their worst nightmares. Some try to hide from the relentless creatures, while others muster the courage to fight back or search for an escape route. Each guest must confront dire circumstances and make difficult decisions as they desperately strive to survive the horrifying ordeal they find themselves in.
However, the island holds numerous enigmatic secrets that deepen the mystery and uncertainty surrounding their chances of escaping the dreadful fate that awaits them