Oyama Mihari is a high school girl with an athletic and very slender figure. She has dark brown hair that is pulled back in a red ribbon in a pigtail. She also wears a gold hair clip in her bangs that her older brother Oyama Mahiro gave her during her first year at school. he has an unemployed or NEET older brother who he turns into a girl with his experiment and he calls the experiment his "The Oni-chan's rehabilitation project", and he tries to keep the experiment a secret from everyone.

