I managed to get Edo Deidara on a free pull as my only pull in Lucky Stars then you have a guy above me with 5 pulls for shisui. Then on another occasion I managed to get Hokage Minato for 2.4k coupons or so.

Then you have some naruto online youtuber spend over 25k and never got an event ninja from Lucky Stars (the jackpot ninja). (can't remember who he was honestly)

So take it as you will, it's "random".

Dropped 10k to get Shisui...didn't get him :L

Did get Konohamaru though and lots of power items. Only gained 2k power from it though sadly. But oh well. Also stole 1st place for Gold Essence :p