The Charm of Soul Pets (WN) - Chapter 1682: One Billion Heaven Demons

Fight. Heal. Survive.The Integration didn’t just change the Earthen Union—it tore it apart. Monsters, mayhem, and madness turned civilization into a battlefield.Yet, while the world crumbled under the weight of despair, David felt something unexpected: he felt at home.Even after being forced into the [Cleric] Class, David refused to yield. He adapted, turning his unwanted gifts into tools of both healing and destruction, forging himself into a battle-hardened healer unlike any before.

A boy from 21st century Earth, met an accident and later was reborn in Naruto’s Ninja World.
He is born in Uchiha Family and becomes the useless brother of Itachi Uchiha and Sasuke Uchiha…. Let’s see how he changed the Naruto world.

- Description from Novelupdates

Ajax used to coast through life before his parents died, after that he focused hard to try get his life back on track but that wasn't really happening and it all ended the day he got mugged. Given a second chance at life he now looks to become someone who matters and is willing to work hard from the beginning to make that happen.

After 2000 years has passed, the ruthless demon lord has just been reincarnated! But his aptitude at an academy for nurturing candidates for demon lords is, “Inept”!?