Hirose Motoka

A girl who was adopted into the main character's family because she was Erina's sister.

She is the complete opposite of her older sister Erina, and is the mother figure of the Hirose family, taking care of the household chores and balancing the family relations.

Surrounded by many unique people, she is always on edge, but she gets along well with Nono, who is a relatively sensible person, right from the first meeting. Due to a mispronunciation of her name, she is now called "Tomo-chan" instead of her real name, "Motoka".