If I were you, I'd probably just get the frags you need for Asuma WB.
It's going to be a really low possibility, so you should only rely on free pulls to get TB Naruto.
Oh and by the way, I once free pulled Gakido three times from the wheel, so whilst it seems unlikely, it is possible.
Seriously though, with the low percentage of the possible pull rate, don't bet your luck on it and keep spending in the belief that you'll get him.