Infinite Bloodcore - Chapter 4: I Will Protect You

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.

Ryu Han-bin, the main character who fell into a new world after being chosen as a ‘suitable person’.

Because of the error in the guidelines, the training is repeated endlessly…

An orphan dies while saving a bus full of children. For saving countless lives, the Universe grants him the opportunity to transmigrate to another reality.

There he realizes his dreams of supporting his new family and opening a company that will shake the foundations of this new world. He will be known as the MasterChef of the gods, a superstar singer, the best Mangaka to exist, the best Director, the businessman of the millennium and many other adjectives.

Childhood sweethearts.
The most popular person in school is my childhood sweetheart.

- Description from Novelupdates