The Demon King Is 18

Read manhwa The Demon King Is 18 / The 18-Year-Old Demon King / 마왕18세
Ravis Vindica, the son of the great Demon King who rules the Demon Realm, wipes out an annoying demon clan on his own and is punished by being exiled to the human world.
Now living in the body of an ordinary student, he discovers that his demonic power, which shouldn’t be usable, reacts to “evil.” As he slowly relearns how to use his strength, he begins searching for a way back to the Demon Realm.