In modern Japan, there is a thousand-year-old fox spirit named "Konnno" who watches over people as she lives her life. Having lived for a millennium, she has no one older than her and harbors a lonely feeling within. However, one day she meets a petite woman who, like her, is not human...? Upon discovering a certain commonality, Konnno asks, "Can I call you 'Onee-chan'?" They are neither human nor sisters. Yet, their daily lives unfold as a heartwarming comedy as they connect like sisters!