Dark Old Demon

Roy's life was nothing special. The only thing commendable was the last few moments when he saved a mother and her child from a drunk driver.
...
It's really an egg! Damn it, what kind of monster have I become? Did I fall into Hell instead of making it to Heaven??
Join Roy as he ventures through various worlds with the Custom Made Demon King System—a system that allows Roy to draw anything he can imagine and create it through exchanging souls!

Custom Made Demon King

To Roy, Dendera Fortress was only a temporary stronghold for recruiting troops. After occupying it, Roy had not thought about staying for long.

However, when Roy and the others first occupied Dendera fortress, it was still intact, but when they left, it had become utterly dilapidated. In addition to the damage caused by Roy experimenting with magic, there was also the destruction wrought by the summoned demons. Even if the Bracadans could retake the fortress in the future, it would probably require an overhaul before they could use it.

During this period of time, Benia summoned more than 10,000 low-rank demons and more than 4,000 middle-rank demons from the Abyss. In addition, in the last two days, Roy summoned over 140 high-rank demons. In this mixed army, there were about fifteen thousand demons.

Zombie Siege