Aoi Nishimori’s parents moved to another city for work, but Aoi didn’t want to transfer to a new high school. She stays behind and lives in an apartment by herself. Shūsei Kugayama moves in next to Aoi’s apartment. Shūsei is a very popular student at their high school. Due to a mistake, Aoi makes the sprinkler go off in his room. Until Shūsei’s room is fixed, he stays with Aoi.