Koharu is a single mother of two, Nozomi and Riku. After the accidental death of her husband Shin, she tries to seek welfare but is deemed ineligible as she doesn't meet certain criteria. When asked if she has any relatives who will be able to provide her financial aid, Koharu says that she has no living relatives. Her mother, Sachi, had abandoned her and her father 20 years ago, for her current husband Kentaro. Since that day, Koharu has had no contact with her mother, and her father had also passed away.