From the First Day I Worked as a System

"No! I am the system? Why don't you say I am an NPC?" "Okay! Then you are the NPC." "Damn! Don't you have any idea?" "As long as you are happy!" ........ The protagonist accidentally traveled through time, and unexpectedly became a "slave system" for a group of people. Yes, you heard me right, it's a group of people, not one person. It's not a supreme system, it's more like a slave system.