Kaede is like a less estupid TOSHINOU KYOKOOOO
But remember, Kyoko gets very good grades, so “stupid” isn’t quite the word . . .
More of a Genki Genius Ditz, I’d say.
https://tvtropes.org/pmwiki/pmwiki.php/Main/GeniusDitz
The more I think about it, the more necessary these family/Kaede interludes strike me. They show that the change in Koyuki isn’t laser-focused on Konatsu, and she can open up and have fun with a friend and with her own family, rather than Koyuki just going from being isolated from everyone to being isolated from everyone except one other person.
Or maybe it is Love Triangle, Cheating, and NTR. But I think not.