Miki, not Kagami. Learn the difference. And hence not alternate_hairstyle either.

It's understandable, since you don't really see a lot of the other Hiiragi sisters in the anime.

Well, the sisters are irrelevant here. Miki is the mother.

Oops, that's what I get for not checking the pixiv tags. In my defense, this guy's way of drawing Miki is almost the same as his Kagami: see post #349566.

perhaps Kagami took alot from Miki appearence wise. (Not that unusual since Konata and Miyuki look similar to their mothers)

Perhaps this is Miki in her high school years, or at least before she married Tadao (lucky bastard that he is)?