The grin doesn't fade. If anything, it gains something of a cheeky edge to it, as if he knows something the others- or other, given it's Josuke- don't.

Turns out that's indeed the case, as Noa's ghost shows up soon after (and Josuke gets to deal with Zahra). "Heheheeee....what'd I tell y'?" he laughs, grinning widely at the optimism in the air. The slip ups on neechans and the like only makes it better, really.

"I think 's abou' as good as y' could've made it!" he compliments further.