Well, very few tsundere (yes yes, even loli ones) manage to win me over, and even then, I usually have someone who I like better than them. I like Eri in school rumble, but I like Yakumo better, although I don't mind either Flag or Onigiri. I like Louise in Zero no Tsukaima, but I like Siesta better
Shana... well, she has her good and bad moments, not that she's that bad, but I prefer Kazumi
Only character I liked from the first moment that displays some ojou/tsun qualities (not an established tsundere character) is Shinku, from what I recall.
But yeah, the show is called Shana