The Hell Walker

Y/n was an 14 year old boy when one day he was sent to the underworld known as hell by mistake, when he was there he was alone and scared and soon he found him self cornered by a demon he closed his eyes waiting for death but just as the demon was going to kill him he, someone killed it by ripping its arm off and then ripped his head off, when Y/n look at the person the man was wearing green Armor and looked very dangerous then person looked at you Y/n then heard a voice asking when he was here when Y/n told the man what happened to him he decided to take Y/n in and train him...after a few years Y/n had become a Night Sentinels as well has having the mark that the demons all fear the same mark his father had the mark of the Doom Slayer