MTL - Full-time Master: Buy Excellent Era at the Start - ~ Explanation of the plot

The Invincible Immortal Emperor reincarnates, taking over the body of a student at the Huaxia Medical College. He displays extraordinary skills both in combat and medicine.In his previous life, he was the undefeated War Emperor and the supreme master of medicine. Yet, he found himself ensnared in the mundane affairs of the world, confronted by endless temptations.Would he lose himself to these temptations or remain steadfast in his principles? Would he succumb to despair and decadence, sinking into oblivion, or would he rise with strength and resilience, reversing the course of destiny?As he sets forth on his path to reclaim his status as the Immortal Emperor, he vows to make the ghosts and gods of the myriad realms tremble in fear!

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

Corporate slave Alexander dies with only one regret—not finishing the fantasy novel in his hands. Fate has a twisted sense of humor when he awakens as Alexander Flamingo, the perverted villain destined to be expelled and killed in that very story!Armed with complete knowledge of the original plot and a mischievous “Harem King System,” Alexander plans to rewrite his fate. No longer the one-dimensional pervert of the novel, he'll use his future knowledge to manipulate heroes, seduce heroines, and rise from disposable villain to the true mastermind of this world.The system grants him power through every relationship he builds—but can this calculating reincarnator use his second chance to avoid his predetermined death and become the ultimate Harem King? One thing's certain: this story won't follow the original script.

This is a story about Gong Lixin who was the young master of an ancient underground palace in the ancient times. He was raised by his master and forced to partake sexual relationships with numerous people to cultivate his Yin Body. His master who has a Yang Body was going to absorb him after he has reach a level to become stronger. MC refused and killed his master also dying at the same time. Then he transmigrated to the modern time and thinking he will enjoy peaceful life, the end of the world arrived.

Being someone with no special powers except for his martial arts, see how he use his martial arts to dominate the times and find his lovers.

- Description from Novelupdates