MTL - Marvel: Start with Summoning the Shadow Troopers - Chapter 221

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!

In his past life, Ethan Steele was an ordinary man living in a modern world—working a dead-end job, struggling through the monotony of daily life, and haunted by regrets of missed opportunities.At the age of 23, his life came to a sudden, unexpected end in a car accident. As his consciousness faded into darkness, he was sure it was over.But fate had other plans. In the divine realm, the God of Fate watched over the balance of life and death.Ethan's untimely death was a mistake, an anomaly that diverged from the preordained path of his destiny. It wasn't yet his time to die, and so, the god decided to give him another chance.“You were meant for greater things, Ethan Steele,” the god's voice boomed. “To correct this error, I will reincarnate you in another world—one filled with magic, swords, kingdoms, and adventure. You shall be reborn, but you will not remember your past until the appointed time. There is, however, a... complication.”By divine error, the god accidentally bestowed Ethan with the Harem God System without having any idea about it.This system is a powerful, reality-bending system that would allow him to charm and seduce influential women to build his harem, growing in strength and power with each conquest.“Your memories of Earth will return on your seventh birthday. I hope you enjoy your life here in this world”And with that, Ethan's soul was transported to a new world.

I became the Heavenly Demon’s dog.

It was a time where demons roamed the earth and chaos reigned. The story took place in Luoyang, the legendary capital of the times. During the night, one could find people holding on to their food with dear lives as they faced off against stray dogs, people with weapons in hand vowing to fight against Fate to their very last breath. There was bloodshed everywhere as some died meaningless deaths, while the strong tyrannized the weak and the truth was frequently hidden. Some of the citizens had completely lost their mind, while some died on their travels. Most importantly, the words of a certain youth caused much panic in the human world. It was a time of little warmth as nights in the capital were frequently accompanied by gusts of wind and rain, and it would be covered with snow during winter. Such were the days…

- Description from Novelupdates