"Oh, I wouldn't hope to have such a nice date as you!" He laughed, happily to brush off the joke even if Momo did seem sort of out of his league in the general sense. It was sort of the same way Todoroki did too, and a little lesser obvious Iida. They were all rich, and had famous families. It was the sort of thing Kirishima just couldn't comprehend, but it was pretty amazing that they'd all ended up together in class, all of them wanting the same things. Being heroes.
He grinned a bit. She might've seemed off, but her stomach seemed more than happy to be onboard. Nodding along, he simply walked, keeping a loose hold on her arm so she could shrug him off if she suddenly decided to, but he was usually one of the least threatening dudes in class, mainly because he just didn't go crazy over girls like the other boys could. He wasn't going to ask about why she came, but it had to be good reason. They all did, right? Even if it was a mistake.
"Uhm...yeah! There's an actual tea house...I don't know if they call it a tea house, but they have that stuff and like cakes. It's kinda frilly..." Really, Kirishima would never dare to go there without a girl present, and he wasn't incredibly into the whole tea thing either, but, you know. "I bet you'd really like it."