Villainess Level 99: I May Be the Hidden Boss but I'm Not the Demon Lord[a] is a Japanese light novel series written by Satori Tanabata with illustrations by Tea.

Hoping for a peaceful life away from her absent family, she decides to level grind in order to survive, spending her childhood doing so.

With her plans turned upside-down, Yumiella must navigate everyone's wariness and the country's politics to find her place in the world and join the original game's heroes in defeating the Demon Lord, all while attempting to dispel the negative preconceptions regarding her dark hair and magic.

Written by Satori Tanabata, the series began serialization as a web novel on the user-generated novel publishing website Shōsetsuka ni Narō on June 15, 2018.

It was later acquired by Fujimi Shobo, which began publishing it as a light novel with illustrations by Tea under their Kadokawa Books imprint on May 10, 2019.

[22][23] It is produced by Jumondou and directed by Minoru Yamaoka, with scripts written by Fumihiko Shimo, character designs handled by Hitomi Kaiho and Lo Ho Kim, and music composed by Kana Utatane.