Upon enrolling at Jougaouka High School, Atsushi Arisawa had come with the expectation of being near his childhood crush, Masami Shibata, affectionately known as Ma-chan. What he didn't anticipate was that Masami had already departed from the institution and, in his place, was his sibling, Masayoshi, occupying the role of school nurse. Confusing Masayoshi for Masami, Atsushi was taken aback by what he believed to be a total deviation in personality. Meanwhile, his friend Kouji Inagaki had developed an infatuation with him and was unceasingly attempting to engage him romantically. Thus, Atsushi found his life at Jougaoka unbearable until he glimpsed the favorable characteristics in the new Ma-chan. This realization was short-lived, however, as he ultimately discovered Masayoshi's true identity.