Killing Game: My Opponent Became a Box

Li Yi, who carried the usury, was sold to a mysterious organization K by the Mafia.
He had no choice but to participate in a killing game whose bonus was as high as 100 billion!
Fortunately, he activated the human-box system, and the dead would explode a box in front of him.
"The corpse box was opened successfully!”
"You will be rewarded with advanced fighting skills!”
He was constantly learning new skills and becoming stronger. He was determined to get the 100 billion bonuses!