Somehow i've been convinced that they've been hanging out since middle school, but wiki says first year of high school, so it probably wouldn't be weird for them to not visit each other's homes yet.
So is the running gag going to be that every sibling is/becomes a fan of Nozaki?
Just, later down the road a sibling chapter with them all sitting around, "that Nozaki guy sure is great."
well, theyre friends during school but given how often she's flirting with other girls idk if she's brought up her sister, after all, idk if ppl know mikorin has a pet cat