Hitman In The Apocalypse: I Evolve Infinitely!

Rein was a notorious hitman working for a mysterious agency under the alias 'Agent X'. He was known to be the most dangerous hitman the world has ever seen, with an almost perfect record. It was said that no target had ever escaped his grasp, making him a monster that every notable figure in the world feared. Until, one day, and seemingly out of nowhere, the world shifted completely as humans started turning into flesh-eating monsters, and all the living creatures in the world became terrifying monsters. Cities burned down, and countless people died. However, unbeknownst to Rein, this was but the start of his journey. From a normal human to the pinnacle of power. [Your body has entered the Evolution cycle.] [You have been granted the blessing of Essence.] [You have killed a Level 1 Undead.]