Jishou! Heibon Mazoku no Eiyuu Life: B-kyuu Mazoku nanoni Cheat Dungeon wo Tsukutteshimatta Kekka

Chrono Alcon, a young demon, traveled from his small village to study at a prestigious school connected to the Demon King's Castle itself. Determined to keep his country-bumpkin status a secret, he tries to keep a low profile... but when his groundbreaking performance in his first test attracts the attention of not only his (gorgeous) classmates, but the Demon King herself... Chrono realizes his dreams of a "happy, normal school life" may die in the dungeons... just like him!

(Source: Kodansha Comics USA)