The F-Level Killing System Starts at the Beginning, and Upgrading Depends Entirely on Killing!

He time-traveled into a useless person without any superpowers, but he didn't expect that when the global death game was about to begin, he accidentally unlocked a system. Killing system at your service! In this game where death is everywhere. Ding——The target is found to be an A-level ability user. Do you want to execute the killing system? The kill was successful and 300 killing points were obtained! Ding——The target is found to be an S-level ability user. Do you want to execute the killing system? The kill was successful and 1000 killing points were obtained! Ding——If you discover an SSS-level ability user, do you execute the killing system? The kill was successful and 10,000 killing points were obtained! In this world full of death, I am killing! This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.