Well the Tiger Dojo is a place that ruins your idea about Illya and Taiga though. Aside from that if you collect all 40 and finished HF you'll be able to get 3 chibi cut scenes which are for getting the first 30. And the Gao! sign for all 40 and completing the entire game with all of the CGs covered. Although there is one set missing, but that's where there Gao! sign comes in, since it fills that one blank slot.