there are in total 9 scrolls. we have up to the Invasion of Pein. there's still:

- 5 kage conference

- great ninja war

- the return of legends?? (i translated this directly from chinese but i haven't unlocked this scroll on my cn acc and i can't tell you anything about the ninjas within it, nor can i pinpoint any ninja that might fit this arc in the naruto manga)

- edo tensei

- bonus/festival ninjas (includes ninjas like cny kiba, fukurokumaru, swimsuit hinata etc.)

i would just suggest you spend the coins on whatever you need now. you can/ always save up again later.

massive disclaimer that ALL the ninja in that scroll are event-only ninja

i guessed that was why you commented haha

unfortunately the ninja collection system only lets you collect the more common, normal ninjas in the game