Nanao, who is uncoordinated and can’t swim, excels only in academics. Yet, no matter how hard she tries, she can never surpass her classmate Idogawa-kun. She refuses to lose! Determined, Nanao decides to attend a cram school, but to her surprise, Idogawa-kun also goes to the same one. Over time, her sense of rivalry gradually turns into a faint crush. This is a coming-of-age story of a clumsy but earnest girl and her summer of growth.