Sorcerer's Handbook - Chapter 521: Inferno of Tribulations Demi-God

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!

The world froze.Literally froze. The chattering students, the falling cherry blossoms outside the window, even the dust motes in the air – all suspended in perfect stillness.“Oh wonderful hero,” a melodious voice echoed through the room. “Your world faces a terrible crisis, and you have been chosen to—”“No,” he said flatly.A pause. Then a shimmer of golden light coalesced into the form of a beautiful woman in flowing robes. She blinked at him. “I... what?”“I said no. I'm not interested in whatever quest or destiny you're selling. Pick someone else.”The goddess's perfect features creased in confusion. “But... but you've been chosen! The prophecy speaks of a warrior with a fierce spirit, one who—”“Lady, I don't care about your prophecy. I've got enough problems here without adding some fantasy world's issues to the mix. Now un-freeze time and leave me alone.”“You don't understand,” she pressed. “Our world is being ravaged by the Demon King's armies! Millions will die without—”

The strongest Demon Lord dies, and reincarnates as a human. Not only that, he because of various incidents turns into the hero’s best friend.

Follow his journey as he tries to help the hero escape his fate, and on the sideline to conquer the continent while he’s at it.