After the jacketed man left, Seiji attempted to interact with other humans as well as non-humans.
No matter what he did or said in front of everything and everyone, they all had zero reaction and continued to do whatever they were doing.
Seiji was now certain that all of them were similar to NPCs!
NPC stood for non-player character. These characters were common in just about every game.
Seiji had played various open-world RPG games in his past life, such as Assassin's Creed, The Witcher, and so on. There were large amounts of realistic NPCs in those games that walked, talked, and performed various actions.
But no matter how realistic they were, they were still only fake humans that would act according to their programmed actions, just like puppets or humanoid androids that were capable of moving on their own.