World’s Strongest Sorcerer Gets Reincarnated

Story:

En No Ozunu is a powerful mage who lives the rest of his life peacefully deep in the mountains in the company of two demons: Zenki and Goki. At the height of the Asuka era, he was considered the country's chief heretic, Yakuozunu, infamous for blocking the way not only to the capital's authorities, but also to the Gods themselves. Realizing his imminent demise, he performs the technique of reincarnation and… …and finds himself in the body of a modern-day Japanese schoolboy being mocked in school? Meet Japanese-style fantasy with magic and hierarchy!