Devil Returns To School Days

Good grades, a handsome appearance, above-average fighting skills, and a little bit of righteousness.
On the eve of his graduation, Kim Hyun-sung gets pushed off a rooftop ends up in a vegetative state.
Unable to die, with only his hearing and consciousness alive, he spends the next ten years in hell until he suddenly returns to the day the bullying began.

Also Read This Manga Online For Free: From now on, I will be the father of the mage