ada is filled with regret. In junior high, he dated a girl named Ai Mizuno, but her free-spirited nature, the very part of her he fell in love with, ultimately drove them apart. After Ai moved away, their love should have faded into a bitter memory. But during the summer of Yuzuru's first year in high school, she suddenly reappears in his life and, without a trace of resentment, tells him that her feelings haven't changed. Yet old wounds and misunderstandings resurface. Can the two of them overcome their past, or are they destined to carry this regret forever?