Akuyaku Reijou ni Nanka Narimasen. Watashi wa『Futsuu』no Koushaku Reijou desu! - Chapter 78: Memory and breasts.

A useless prince, yet brimming with kindness and compassion—his smile as warm as sunlight, illuminating this darkened era.But that was merely a mask, hiding the poisonous and mad nature beneath.A monster lurking behind a gentle shell.A system that feeds on stolen Heroines.He will outplay destiny—and rise as the world’s ultimate villain.

Roy’s life was nothing special. The only thing commendable was the last few moments when he saved a mother and her child from a drunk driver.
…
It’s really an egg! Damn it, what kind of monster have I become? Did I fall into Hell instead of making it to Heaven??
Join Roy as he ventures through various worlds with the Custom Made Demon King System—a system that allows Roy to draw anything he can imagine and create it through exchanging souls!

When he woke up, Yang Yuan found himself reborn.

When he was one year old, “Ah, not only rebirth, but also transmigration.”

At the age of three, “Goldfinger is finally in place!”

Portable space is handy.

Fourteen years old, “What the hell is my golden finger?”

Yang Yuan screamed in the sky…

Thirty-year-old, Yang Yuan, who was hugging from left to right, stood on Emperor Tread Peak, pointing to the vast land, “This is the country that I have conquered!”

Omg, golden fingers are so fragrant!

- Description from novelbuddy

In 2040, The Earth was bathed in powerful radiation when a star went supernova, this radiation granted 50% of humans superhuman abilities but also created a nightmare for them as animals, insects, and carnivorous plants were mutated and became overpowered with intelligence, human started teetering on the brink of survival, a boy with no powers and no father, with a mother in a coma, seems destined for obscurity, but one night changed his life, with a new found hope to cure his mum from the everlasting sleep—Gene Elixir— he went on on a journey that would reshape his destiny...~Voracious Sovereign... Gene Devourer...Pray you won't be devoured by this power you wield which hunger is insatiable~~You call yourself an opportunist... But... you aren't free. A hungry man is not a free man...~