That's a weird thought - and kind of an uncomfortable one. Granted, their original worlds didn't come up much back in Ryslig, but having the topic come up now just... drives home how much this "other" him didn't know Yukio at all, and vice-versa.

He can't get into that, though. Can't show it. So there's only a moment's pause, as easily a second taken to think as anything else, before he replies. "There was a type of organism in my world called mushi - but some called them 'the green ones', or along those lines. They were essentially the type of being closest to my world's source of life."