Each Treasure have this *on at the top right corner where you can see the ninjas that the said treasure contains .. It is color-coded ninja names in that box, blue are commons, purples are rares, yellow are super rares and the red one is the ultra rare which only drops by fragments .. Zabuza [Edo Tensei] is one of the Rare ninjas but Toroi and Pakura, they are only Common ninjas ..

Edit : Rare drops is also not exactly per 60 seals .. there are times rare drops at 50 seals only while some others drops with 70 seals ..