So he is in modern China... lucky he is not arrested already. Even if he doesn't break some random law, he surely has no papers.
I went looking for information on this weird money... I'm not sure about the state of Lu, but allegedly there were many instances of
knife money around the Warring States Period, which sounds like something you'd make up as a joke in a manga - "even the money was warlike!" There was also spade money. Personally I think it's good we converged on coins and bills instead.