Doomsday Descends: Am I Actually the Zombie King?

[Zombie Fusion System, Apocalyptic Power Fantasy]

The apocalypse arrives, the world is in crisis, and zombies run rampant. Zhang An transmigrates into this world and grabs a knife, ready to kill zombies to stay alive!

Ding! Congratulations, Host, you have bound the Zombie Fusion System. You can fuse low-level zombies to increase your combat power.

What? I've actually become a zombie?!

Hunted by ability users and pursued by other zombies as one of their own, Zhang An has no choice but to keep leveling up and strengthening himself.

How did I become the Zombie King before I even noticed?