Wasteland's Only King

Yu Jin awakens a system before the apocalypse comes. When he is feeding a stray little calico cat, a sentence pops up before his eyes.

[You have successfully persuaded and contained the Tier Three Mutated Beast King ‘Shadow Leopard’, Wasteland Points +800! Acquired Ability ‘Dark Element Control’!]

While Yu doesn't know anything about the pending doomsday, somebody does.

Yin Yao, daughter of the richest person in Daxia, is a Reincarnator.
She knows that seven days later, a game called “Wasteland” will invade reality.
Half of the global population is forcibly transported to an Alien Wasteland, struggling to survive in a world filled with powerful Infected Bodies and terrifying Mutant Beasts!
In order to survive better this time, she goes for Yu immediately.
"Something you need?"
"I want to join your Environmental Protection Club."
"You're the Dance Club president; joining our Environmental Protection Club doesn't seem appropriate."
"I can quit."