Mio Hasekura is a helpful high school girl who looks after her workaholic mother and others at her school, which has earned her the nickname "Mom" among her classmates. Mio is very fond of her late father who died when she was younger, and hopes to find a guy like him someday. On her way to school one day, she comes across a man collapsed on the side of the road who is very different from her father and Mio helps him out.