Umi Katou

Presenting herself as a distant relative, Umi arrives alone on Torishiro Island during summer vacation to take care of protagonist Hairi's daily needs. Her true origins, however, run far deeper: she is the daughter born to Hairi and Shiraha in the future. Driven by the desire to prevent her mother's death in childbirth, Umi harnesses the island's mysterious power to repeatedly loop through time within an endless summer, quietly weaving cherished memories for both of her parents. Her presence ties together the story's most essential threads, making her the emotional core of the entire narrative.