Kaoru Sugimura is a high schooler with poor grades and a private interest in S&M, fixated on his perfect, popular childhood neighbor Nana Chigusa. The two have drifted apart over the years, and Nana is buckling under the pressure of cram school and exams. After one of Kaoru's hidden toys ends up in her hands and leaves her unexpectedly calm, the pair begin secret sessions they call 'breathers', kept from classmates and family alike.