Responses
could also be a family friend type of thing. I'm not sure how it is in Japan, but ik in a lot of places, especially Asian countries, they call each other cousins and aunties/uncles even if they're not related, its more of a community thing as well as respect, so could also be like that
that too
They're either 3rd cousins or even more distant then that, Akiha didnt know the mother nor the father and since they briefly met they must be in laws of in laws or something. The japanese tend to keep track if you're even the slighest bit related but if youre not 1st or 2nd cousins its not a big deal at all anymore. I thought they might have been 1st or 2nd cousins so i reread the whole thing to make sure and i dont think its likely at all.