Mabeopseosaeng 

Certan was the prince of the demon world who wrecked havoc a long time ago. His father, the king of the demon world, had his soul sealed in an octagonal tablet and he sent to the human world… By accident, he got stuck with a boy named Go Jin-Yeong… ‘Let’s conquer the martial world with magic!’ The popular martial arts novel, Magic Scholar, returns as a webtoon!