[Oh. She'd...never really had to explain it before; back home, honorifics were so culturally prevalent that it would have been strange not to hear it. And even here, most people seemed to either be familiar with the tradition, or went along with it anyway.]

It's the way we refer to people back home.

Like, Takeru-kun is Takeru-kun to me, and I'm Hikari-chan to him. Because we're friends and the same age. But if we don't know somebody, or they're a little older than us, we can call them -san instead.

[There were others, of course, but those were the only relevant ones in the moment.\]