It Seems That I've Slipped Into a Different World. Also, My Gender Has Changed. - Chapter 75: The Secret, Confidential Letter

In the vast Marvel universe, where superpower was still slowly growing in its infancy, several peerless superheroes tried to find their path in The Marvel Universe. A young adult named Ron from modern Earth unwittingly stumbles into such a world and begins his journey with an unknown power. This is a magnificent yet unknown true marvel world! This is the story of a normal young adult and his adventures!

- Description from Novelupdates

A young man who had longed for stories of good and evil since childhood lost his life in a tragic accident and was reincarnated as a boy named Chrono Mak in another world.

He learned that in this other world, there is magic and witchcraft, and depending on how you train them, you can become as strong as you want to be, so he decided to become the strongest demon king in order to recreate the story of justice and evil he once dreamed of.

Growing up with eccentric materialist parents who left him in the care of his grandfather for a job overseas, Zhang Heng had learned to adapt and be unfettered by the oddities and challenges in life. But he would soon learn the baffling truth about the world he thought he knew when one day at midnight time froze and he found himself in a world so quiet and still it was deafening. That night, he discovered that he had 24 hours more than everybody else and thus, marked the beginning of his adventures. The mysteries surrounding his newfound ability only deepened when a strange old man claimed to have given Zhang Heng that ‘gift of time’ and recruited the young man to participate in a cryptic ‘life-changing’ game on his behalf. Little did Zhang Heng know that accepting those terms meant embroiling himself in many versions of reality and exposing himself to the hidden secrets of the world—a decision he could never undo.