Scars

"Ughh, my head hurts... Where the hell am I?" He was confused about his predicament when he woke from his slumber and sees his body reclining on top of a mattress

[You don't remember...? You fainted after you overwork your body to the bone, guess you're still naive. Your body may possess a case amount of vigor but you haven't properly rested when it came down to your needs. That demon he calls himself, Lucifer took your place and allowed not a single person to visit you. But he did assign you a guard whom he chose was the most suitable and someone he can trust with his all]

"You're awake, I can't believe that the mighty Demon King would be brought down not by a blade but by his fatigue. I guess you're still a child even though you possess the body of a fully grown adult. I suggest you shouldn't push yourself very often~ Hey! What are you doing?" Silvia was stunned after he tried to leave in his current state and before he could reach the door his vision became obscure