Mao

Mao (マオ), otherwise known as the Demon Lord (魔王) is the antagonistic-turned-support character of the series. Upon confronting the Hero Party a the series' beginning, the Demon Lord was accidentally sent to the past with reduced size after Yusha's sealing spell went awry. She becomes a teacher at the Adventurer's School in hopes of preventing Yusha and her friends from ever becoming a hero, but eventually gives up on the idea.