A man washes ashore with no memory, three families locked in cycles of guilt, and five years of slow rot on an island that severed itself from the world. The mystery pulls you in because every answer rewrites what you thought the whole story was about. The pacing collapses under the weight of its own ambition, cramming visual novel scope into twelve episodes, but that collapse is almost the point, it mirrors how desperately everything on this island is falling apart. If you can sit with narrative whiplash, the time travel mechanics don't feel like a twist; they feel like a funeral for people who never got the chance to change.

A man washes ashore on Urashima, a remote island far from the mainland, with no memory of his name or home. He recalls only that he has traveled from the future to save a certain girl. Five years earlier, misfortunes struck the island's three great families and bred suspicion, and the islanders cut off contact with the mainland and began a slow decline. Three girls from those families may hold the key to saving it, but old traditions bind them. After a song sung by Rinne Ohara reminds him of the name Setsuna, he adopts it as his own, and she takes him into her household as a servant. He learns of the island's folklore and a disease that keeps its victims out of daylight, and he begins to wonder whether his mission is larger than one girl's fate.