Almost any one so far I know, its all random tho.
Sometimes you might get a really easy ninja to get, other times a rare might appear,
like young Obito or Itachi.

Its also a nice place for some extra materials to upgrade items/ninjas :P

Thanks, I was unsure about it :)

Im beginning to see different ninja as I level up. Today I got some Gaara and obito boy frags

I've seened Gaara Itachi Sasori

Gaara , obito , sasori, and itachi , kakuzu