Bog Standard Isekai - Chapter 11Book 4.

Overnight, she was betrayed by her fiancé and sister, and was forced by her family to marry a fool. On the wedding day, everyone was waiting eagerly to laugh at her and see how she would get her foolish husband to put on the wedding ring. However, she took out her marriage certificate, which shocked the world, because the man on the certificate was not her ex-fiancé or that fool, but...

“You’re not taking me to bed. Ever.”

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...~

He had served in the strongest Special Forces, Heavenly Sword Special Force. As the commando of commandos, he created the Netherworld in the western underground world and became the formidable Oriental Yama. He said, “I’m Liu Feng. I’m adept at two things: killing and saving. If I want to cure someone, even ghost soldiers can’t take him away; if I want to kill someone, God can’t save him.” Now he was the bodyguard of Yang Shiwen, who was the daughter of the richest family in Donghai City and suffered from a rare disease. Could Liu Feng save Yang Shiwen’s life with his amazing art of healing? What would happen to his double life?

- Description from Novelupdates