Return of the Runebound Professor is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Magus Vermil was a scumbag — the most hated professor at a magic academy. Then someone murdered him. He never would have been heard from again if not for a lost soul from Earth by the name of Noah Vines. Transmigrated into Vermil’s body, Noah assumes the man’s runic powers and extensive list of enemies. There’s just one problem. Noah has to teach class tomorrow, and he has no damn idea what magic is.