Haikyuu: Zero To Almighty - Chapter 64: Watanabe is an Angel

Nanzhi only thought she had traveled into a novel about raising a child. Relying on her many years of “Wilderness Survival” watching experience, she hunts rabbits up the mountain for grilling every day, gropes for fish in the river to make soup, and diligently raises the child. Just when she thought her life was finally looking up and she could have her “second spring”, the “husband” who was rumored to have died hundreds of times suddenly appeared. Wait a second!She seems to have ended up in a novel where the male lead is the main character!Nanzhi? Isn't that the cannon fodder and deposed wife?PS: Not a web novel about farming, the female lead doesn't have a golden finger space system. Just turned eighteen and got into university, not a novel about a powerful female protagonist.

In this world, orphans or just anyone without any hope for this world can apply to become a “walking target”. Their sole purpose is to be a practicing dummy for the students of the sect who train to become “Demon Hunters”. These students need “walking targets” to test their training on living, walking beings of flesh and blood.
In exchange, they will be provided with food & shelter.
Their existence value is lower than a slave, but if they manage to survive a few years they can receive a life long pension.

Xiao Han is such a “walking target”. One time he witnessed a powerful Demon Hunter disposing a demon. When the demon died, a fragment of the demon that managed to escape entered Xiao Han’s heart. No one saw that, and even Xiao Han himself only felt some discomfort for an instant.

But that thing in his heart soon gave Xiao Han visions, and the first one is of a cultivation method which allows Xiao Han to absorb damage to enhance his body. A perfect cultivation method for a “walking target”.

- Description from Novelupdates

Jin-Ho Kang was just another B-rank Hunter—one of countless warriors struggling to rise in a world dominated by monsters and guild politics. When an A-rank dungeon scouting mission goes horribly wrong, he and his team are slaughtered. He should have died.But instead of death, he awakens in an abyss beyond mortal comprehension. A voice older than time itself speaks to him, a decree is made, and the truth is revealed—he is no longer human. He has inherited a power that was never meant to be his.The world forgot him.But he has returned.As a Sovereign.As the Monarch of Shadows.And as the boundaries between life and death begin to blur, the world will soon realize…The true King has awakened.

There are always four kinds of people in the traditional Mary Sue world. The Male Lead, the Mary Sue female lead, the woman who never wanted to see the female protagonist live a good life, and the infatuated man willing to destroy heaven and earth to get the female lead.