I! Flathead Brother! Big Demon?

It's okay to travel through time and become a flat-headed brother. It's also bound to a fighting system. As long as you fight, you will become stronger! I really don't like fighting. What's the point of fighting and killing? I just want to be human again! Bang! You successfully killed an intruder, your demon power +10, your constitution +10... Hey, my damn temper! ! From then on, in this world where spiritual energy revived and everything changed, there was a big flat-headed demon who was either fighting or on the way to fight! This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.