Who is this third character and what is her connection? I have had this image for a while now



I know the brown hair in the middle is supposed to be Taiga Aisaka from Toradora and the pink hair on the right is Louise de La Vallière from The Familiar of Zero, but who is the third character with the red hair on the left? And is there some sort of connection between all 3 characters who are in different anime to make them almost look identical? (e.g. the light in the hair and the face seems to match perfectly yet the shirt on either side doesn't)
I think she looks like Shana from Shakugan no Shana



All of them has similar trait, small stature, and tsundere. All of them also has same seiyuu, she's Rie Kugimiya. And all of them also produced by J.C. Staff.

The reason of why they look similar probably because (as @LoganM says) J.C. Staff is rather lazy with this kind of thing. They also have similar art and animation style among their series even when they have different Character Designer.