Hairi Takahara 「鷹原 羽依里」 is a young man not native to Torishirojima. Hairi grew up in an urban setting, but after an unpleasant incident, he uses the recent death of his grandmother as an excuse to come to the island to take care of her estate sale. Once there, he gets to know the four heroines who are the focus of the story.
Hairi used to be a dedicated swimmer at his high school in the city, but after a certain incident he is now afraid of going into the water. This has affected his personality, and people at the school started treating him like a nuisance. Because of this, he's escaping to Torishirojima for the summer.