Naoe Mihashi (aka Ren's mother) is who Ren lives with. She gets him up in the morning when he sleeps in. She eloped with her husband, Reiichi, and that is why they lived in Creaker Villa for a while. It is also stated (in episode 14, at 7:07) that at the time she moved to Creakers Villia she was still in her twenties (presumably late twenties).
Mrs. Mihashi bears a striking resemblance to her son, Ren, or rather Ren bears a striking resemblance to her. She possesses short, light brown hair that has a slight peachish tone to it. She has pronounced cheekbones and is of a light complexion; with light brown eyes and thin eyebrows. She is appears to be around 162 cm, as she is shorter then Maria who is a few cm taller then Ren who is 165 cm(at his debut). She is normally dressed in T-shirts, shirts, and pants, and wears a dress-suit to work. She has an almost identical embarrassed face, and other facial expressions, as her son and it is shown that she also has a similar personality.
Naoe's father died when she was young and her mother died when she was a senior. She met Reiichi in university but Reiichi's father was against him marrying someone who lived on their own.
After eloping, Naoe and Reiichi lived in Naoe's apartment. They struggled as Reiichi couldn't find a job. Naoe got pregnant unexpectedly and they argued about what to do, but ultimately Reiichi decided to be a house husband.
After giving birth to Mihashi, Naoe took three months of leave, and then returned to college. The school fees, transportation, and such we all expensive, so Naoe applied for scholarships. Even still, the money was eaten up by college expenses.