Probably familiar with her father? At least gone to him for advice a couple of times.

And I think them having known each other in Japan sounds good? Probably not especially close, but they hung out some while their parents were talking? Maki was a pretty shy kid, so she probably didn't make too much effort to be the closest buddies ever, but it was nice to have a girl around her age for when her parents were going on for hours with other adults. Didn't keep in touch when Yuuko moved to Recolle, probably?