Kanako Miyamae transfers to the all-girls Catholic academy Ame no Kisaki hoping to find a girlfriend, since boys make her break out in hives. The angelic upperclassman who greets her, Mariya Shidou, turns out to be a sharp-tongued boy crossdressing to secure a family inheritance. Mariya blackmails Kanako into silence and rooms with her to keep watch, tormenting her at every turn while Kanako's nosebleeds and crushes pile up.