Nishiyama started to sending drafts to manga magazines while still in high school, she submitted her drafts to Hana to Yume 4 times but none of them have been accepted.

Made her debut oneshot in Shuukan Shounen Champion.

Became an office lady after graduating from Faculty of Law of Sophia University.
In 1989, she won the 43rd Weekly Shonen Magazine Newcomer Manga Award for “YUTA”. She later resigned from the company to concentrate on writing manga.

She has an older sister and a younger brother, and is the second daughter of three siblings.

Due to the work of her father who works at the embassy, she spends most of his childhood outside of Japan. At the age of eight, she lived with his family in Vientiane, Laos.

OONO Junji & SHIBUZOME Kazuki were her assistants on Harlem Beat.

Fujimura Mari was her classmate in high school.