What the hell is making games in the Ninja World?

Uchiha Kai: "I'm a hapless guy who traveled to the ninja world. The system is a sham used to make games and train me to be a super game producer. What kind of suffering is this?!"

System: "After testing, this is the earth in 2024. Please complete the production of the first game as soon as possible."

Uchiha Kai: "Okay, okay, you want to play it this way, right? Okay, since I'm not having a good time, let's use the Uchiha way to make the world feel pain!"

"The underworld game, start it for me!"

From then on, the ninja world had an old Uchiha thief who used the Sharingan to make the underworld game to avenge the world.