Kawaki and Himawari’s class goes on a field trip to an uninhabited island in order to create new memories with Kae. Because of its distance from the village, there are all sorts of rumors about the island, and bizarre incidents occur, like the disappearance of the food they brought. The field trip suddenly starts to feel unsettling, but under Hana Sensei’s direction, the students try to work together to overcome these difficulties. Meanwhile, Kawaki suspects the assassin targeting Kae might be lurking nearby, so he steps up his watch.