Everyone Kills Zombies, I Open a Plug-In for the Zombies

The end of the world is coming, and zombies are rampant. Killing zombies can strengthen your body and gain superpowers and weapons. What an injustice to zombies. The protagonist has a "zombie enhancement system" and becomes the boss behind the zombies. Do you want to kill zombies and become a flower protector? Sorry, zombies are not something that just any weakling can kill. Do you want to quickly evolve into a big boss and form gangs to build city-states? Sorry the boss behind zombies disagrees, you are nothing. This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.