Island

The main character washes ashore on the remote island of Urashima, with no memory of his name or homeland. He recalls being a time traveler with a mission: saving a girl from harm. Rinne Ohara, a girl he meets, is familiar with a person named Setsuna and takes him in as a servant, hoping he is the Setsuna she knows.

As Setsuna learns more about the island and its inhabitants, including the three great families and the island's endemic disease, he becomes determined to remember his past and fulfill his mission. However, as he witnesses the island's troubles, he starts to question the true purpose of his time displacement.