In middle school, Ayumu Kamei and Runa Takishima were always at odds. Despite being older, Ayumu was constantly on the losing end, being teased and pranked endlessly by the younger Runa. Now that they are in high school, Ayumu will surely make Runa respect her—or so she thinks. Even now, the charming and witty Runa plays Ayumu like a fiddle. No matter what tricks he plays on her, she falls for them every time, yet even so, she never notices his true intentions. To win, she will have to find his weakness—but Runa's vulnerability is Ayumu herself!