In the Kingdom of Lapanesta, a hero named Yulia "Yusha" Chardiet and her party of friends manage to defeat the Demon Lord. However, their sealing... more>> spell goes wrong and the girls inadvertently send the Demon Lord back in time to before Yusha became a hero. Reverted to the size of a small girl, the Demon Lord, now known as Mao, becomes a teacher at Yusha's Adventure School with the aim of expelling her so that she'll never become a hero in the future. <<less