Sakakino (榊野) is a fictional city in which most of the Overflow universe takes place. There are at least three districts:
1. Haramihama: where the Days series takes place. The following families and characters live(d) there: Makoto and Moeko Itou, the Katou, the Katsura, the Nijou, Inori and Hayato Ashikaga, Natsuhi Ebata, Ai Yamagata, and Roka Kitsuregawa and her mother.
3. Aoi: where Miss Each Other and the PureMail games take place. The following families and characters live(d) there: the Ashikaga, the Sawanaga, and the Ogata. Hikari Kuroda used to live there as well before moving to Haramihama.