When he was a child, Keitarou Urashima made a pledge to enter Tokyo University together with a girl and stay with her. Now twenty years old, he has failed the entrance exam twice, leaving him discouraged and uncertain about his path forward. One day, Keitarou gets a call from his grandmother, who runs an inn, and he thinks moving out will give him a better chance to concentrate on his studies.
But when Keitarou arrives at the building, he finds it has been turned into an all-female dormitory! Currently living there are five girls: Naru Narusegawa, a bright girl who is also aiming for Tokyo University; Mitsune Konno, a playful and carefree freelance writer; Kaolla Su, an energetic inventor; Shinobu Maehara, a shy girl trying to find her place; and Motoko Aoyama, a serious kendo practitioner—each with her own reaction to Keitarou showing up.
Despite the rough first impression, Keitarou becomes the building's manager. Starting a new chapter in his life, he slowly gets to know the girls and their idiosyncrasies, while never losing sight of his ultimate goal—being reunited with the girl from his childhood.