Yukino Suzushiro is a freshman who belongs to the Shakuyaku 'peasant' girls division at the class-based, segregation-enforcing Douwa All-Girls High School. After the entrance ceremony, she enters a greenhouse where she finds a gorgeous sleeping girl, Nobara Himezaki, who belongs to the Botan 'rich' girls school division. After Nobara bravely fends off a pervert intruder, Yukino doesn't meet Nobara again until the dorm room partners are shuffled, and she ends up being the only Shakuyaku girl in a Botan floor, with a Botan roomie… Nobara herself.

Though starkly different, as Yukino is very dutiful and friendly, while Nobara is eccentric and quiet, the two girls find themselves becoming increasingly close to one another.