Aoi Nishimori’s parents relocated to a different city for their jobs, but Aoi chose not to switch to a new high school. She remains in her current city, living alone in an apartment. Shusei Kugayama, a well-liked student at their high school, moves into the apartment next to Aoi’s. An accident causes Aoi to accidentally set off the sprinkler system in Shusei’s room. As a result, Shusei temporarily moves in with Aoi while his room is being repaired.