"Oh! Sorry." He doesn't stumble, but he has to catch himself on a nearby light post. "Uh. Ren. And you're..." Oh, god. "Ka... sumi?"

She's obviously not Kasumi, but the only version of Sumire that he's heard about at length is, apparently, under Maruki's control and feeling sensitive about it, so best to be safe. He's used to calling his own Sumire Kasumi by now; he doesn't know why this feels so awkward.