Oh gods is that... no it's not Japanese clothing. Chinese? Or maybe it really is Japanese - either way it's ancient Asian clothing and he is not the kind of nerd that knows that kind of stuff. He's faintly aware of Japanese mythology and barely aware of Chinese. Hopefully he doesn't offend.

"Uh... it's some kind of ship. A bunch of us from different worlds seem to have showed up here. It's kind of a mishmash of cultures here. I'm Casper. And you are?"

Go ahead, make the joke if you're familiar enough with 90s movies. He's heard it a million times.