[He looks around at Yosuke's hometown. He hadn't noticed it was empty before...]

That is weird. If this were a movie I'd be getting nervous, but...

Maybe you have to think of the people? Like, I dunno, think about specific people or having a town full of people for it to happen? [He almost tests this theory by trying to think of people back home, but he's worried that the people he'd think of were his superhero friends, and even if they weren't he didn't want to surprise Yosuke by having random American people popping up in his "hometown."]