Player: How Did This NPC Come to Life?

The settings are okay, but there are some places where NPCs talk about their NPC identity every day, for fear that others will not know that they are not NPCs. And that old Chen knew that the system did not report the first kill, which was very contradictory. Then how did he know that the first kill was the female protagonist? Even if he saw it, the NPC monster killing itself was not reported, or everyone knew about the female protagonist's system.