Enough, it is clear that the style of mangaka makes all hers characters look similar, when I first saw the cover of the spin off I confused myself thinking that yuu had left Touko for sayaka in fact the style of this fan art gives it a different style to Haru.
Not a lot of artists are great when it comes to height proportion, an inverse example is that it is not uncommon to see people depicting Ui about the same height as Touka and Nemu, when she should be a decent bit shorter, because they just internalize "Oh they are the same age so they are the same size" and don't think of it much further than that.
Looks like one of Sanae's miracles did it again... Well, at least there are 2 new shrine maidens for the Moriya, and one new shrine maiden for the Hakurei, it seems. Well, a happy end's a happy end ;)
I wonder where in this drawing did the artist first start? I think it started at the point of where the lips met, then the artist branched out from there in a symmetrical sort of way.