9 are the number of Akatsuki members, why if 1 Akatsuki member dies, another one joins. That means that every Akatsuki gets a demon under his control.
Sasuke has 3 friends.
It's like a mission-team.
Mayby he joins Konoha.
There are 5 great villages, that means that there are 3 extra hokages.
Now the hokage is always the strongest of the village.
The third was the strongest of the hokages.
That means that there aren't any nins except criminals who are better than the Akatsuki.
Pein has 6 bodies, that means if one body dies, he has still 5 bodies. Everyone says he is the strongest. Now imagine that the strongest character who get killed can revive himself 5 times, that is sick.