It's one of the common rares in the treasure, i got mine at 70 but this doesn't mean anything. Every 6-7 draw by ten in the treasure you get or him or bee samehada (yugito nii is not considered a common rare but a simple common even if is in the destined ninja list). So it's up on your luck. Could be you are unlucky and before getting roshi you get bee 3 times, but is very unlikely.