In April, Tsubaki, a girl who loves hot springs, is excited about her new life in high school. She sees Hiyori, a beautiful girl with black hair, soaking her feet and impulsively asks, "Won't you go to the hot springs with me!?" forcefully inviting her, leading to a relationship that is intimate even before they become friends!? Involving Nagi and Yuka, whom they meet at a café, their hot spring adventure life is full of ups and downs!