[An eyebrow goes up when a switchblade comes out - Yusei's always found appeal in things with utility, so of course he'd find this interesting. But at least he's paying attention, as he'll finally look directly at Otto when the man mentions alternate dimensions. His stare is intense, but given the childlike interest he was showing the arms before, it's hard to be intimidated by it at all.]

Alternate dimensions? Not just another world entirely, but dimensions? [This is a bit out of his scope.] I was dropped into the Underworld once, but I don't think that was necessarily another dimension or anything. [Another realm, maybe? Who even knows.]