Absolute Cheater - Chapter 26: Monster Ranch IV

The world that nurtured the civilization which reached the pinnacle of magic was on the verge of destruction.
The last survivor transmigrated to the past, when the magic civilization started growing, as countless mages were still fumbling their ways through the thorny paths of magic knowledge.
He, who came from the end of the magic era, aim to reach the pinnacle of magic.

- Description from Novelupdates

Reborn as a mosquito? Got a system that makes you stronger by sucking blood?Regarding this start, Chu Sheng was a bit silent.I've already become a mosquito, how much stronger can I possibly get?But no matter what, I have to give it a try...Chu Sheng randomly flew into a room, and unexpectedly, there was a stunningly beautiful girl inside.Not bad! I'll suck her blood!...Gu Yuexi, an Emperor-Level Beast Tamer, the Empress of the Human Race!In her previous life, she only started on the path of Beast Taming at the age of sixty, and her first Contracted Beast was merely of a Low-Level Bloodline, leading to an unstable foundation and her perishing in a heavenly tribulation.Reborn at the age of eighteen, she must become a Beast Tamer at the first opportunity!She bankrupted her family to buy a High-Level Bloodline Demon Beast and prepared for the Blood Covenant ritual!Just as she was about to sign the Blood Covenant with this Demon Beast, a mosquito landed on her leg and took a mouthful of her blood!!“...”“My name is Gu Yuexi. In this life, it seems I'm ruined...”

Nobody thought the end of the world as they knew it would come like this.In a dystopian future, 95% of the population was sent to another universe, one resembling the game Jack had played, “Elder Heir Online”.He would've normally enjoyed such an opportunity, but the company 'DiveCore', from his real world, came along.As long as any of them breathed, his revenge wouldn't be complete.Using his knowledge of the game, and willingness to go through the worst to exact vengeance, he will slowly become what he avoided when he played the game in the real world: a villain.