MTL - Phoenix Destiny - Chapter 696 monster

A teenager who unexpectedly gets transported to the modern world from ‘the world of the immortals’ . He finds himself in the body of an ordinary guy. He wants to go back to his world and for that, he will have to practice to get stronger and investigate the reason why and how he crossed through to this world.

- Description from Novelupdates

A side story series featuring the girls of Kyoukai Senjou no Horizon.

One day, Su Mu transmigrated to an alternate world.This world had martial arts practitioners, Qi cultivators and also various types of terrifying ghosts, monsters and demons.In such a hostile environment, his otherwise-perfectly fine reincarnation system became a death system. For him, death was not the end, but rather, a new beginning. From the system, he experienced the profane lives of tens of thousands of demons! In one simulation, he was cut up, thrown into a pot, and eaten. Then, he became a Bloody Skeleton. In another simulation, he was forcefully conscripted and died in battle. His corpse did not decay, and he became a Drought Zombie. In yet another simulation, he was struck by lightning, and his extreme Yin Qi was converted into Yang Qi. He became a Fierce Thunder Ghost. In one more simulation, he consumed spirits, and his murderous aura filled the skies. He became an Undying Ghost Chariot. Some people cultivated to become deities. One other person died a hundred times to become a demon!

A supreme expert in the Immortal World had died, and a strand of his soul returned to its original body on Earth. Tang Xiu discovered with amazement that ten thousand years passed in the Immortal World, yet only a single year passed on Earth.

Ruthlessly betrayed by his lover and trusted friends, Tang Xiu found that his soul went back to his previous body on Earth, and, despite he spent 10,000 years in the Immortal World, just a year has passed on Earth and many things have changed. Having an unsurpassed knowledge, Tang Xiu will protect his loved ones and go back to the Immortal World to take his revenge.

- Description from Novelupdates