Yanagi is a second-year high school student of Central High School. Most of her friends call her Yanagin while the Science Club President called her Hiro once. Full of crazy ideas and prone to violent outbursts, Yanagi is the ringleader of the Funky High School Girls and is close friends with Ikushima and Habara, although they all deny that they get along well. She also has a lot of male friends, but because of her thoughtless and crude attitude towards high school boys, she has a bad reputation. She likes teasing either Karasawa or Takahiro, randomly picking fights against Ikushima, and provoking Habara.

She is very proficient in karate but she quitted in middle school in order to focus on her academics. Because of this, she ranks second highest in test results, losing only to Nago who she considers her rival.

She was a member of the Archdemon Punitive Force when she was younger and was selected to monitor Habara.