Hirohashi was born in Niigata Prefecture, her family's home being a Buddhist temple.
Due to family reasons, she attended Ryukoku University in Kyoto, a Buddhist university, but in the middle of her first year, she was told by her parents that she could do what she liked even if it wasn't related to Buddhism, so she sought out what she wanted to do.
During her second year, she remembered a radio show she used to listen to in junior high school and became interested in voice acting, so she attended the Aoni Coaching School Osaka while attending university at the same time.
[1] She graduated from the 16th class of Aoni Coaching School Osaka and made her debut as a voice actor in Aquarian Age: Sign for Evolution in 2002.
In February 2007, her profile was posted on the list of graduates page on the official website of Aoni Coaching School Osaka.