Superman Termination Manual - Chapter 582 - 279 Ultraman and Monsters The

After transmigrating, Chen Yu found himself in a highly militarized world. But the “will of the world” had concluded that he was an intruder and put a curse on him.

Violet skies, a world undergoing massive changes, a deficient moon, interlinking voids…
When the world experienced a cataclysmic event,the majority of living things ceased to exist. Although humanity survived by hiding in the last safe zones, humans had to face mutated dire beasts and colossal source beasts that could break through the space barrier and enter the earth at any second.
Luo Yunyang, a young man who grew up in those calamitous times, obtained an attribute regulator and set out to walk the path of supremacy!

- Description from novelupdates

In a world teeming with Titans, Colossals, Gigantic Monsters and Kaiju's, Erian who reincarnated makes his living collecting scraps of low-grade Defective Genetic Serum, realised he transmigrated along with his system.

Follow Erian as he grows to become the strongest Disaster Grade Titan with the help of his Titan System!

Luis, a poor 17-year-old boy, tries his luck at becoming an Awakener to change his fate. However, his dreams are shattered when he fails to awaken a Special Spirit and is instead saddled with a 5 million dollar debt by their planet's colonizers, the Flying Star Empire.His life seemed doomed—until a mysterious system suddenly appeared in his head: The Monster Transformation System. It gave him the power to transform into any monster or animal he had ever seen.From a cat to an eagle, even a horse, Luis begins to understand that his power may not come from Spirit... but from the ability to become any monster.