You can now use all members of the Akatsuki.

You've acquired S Rank in "Earth Shatter".

You can now use Jiraiya, Tsunade and Orochimaru.

You've cleared Chapter Four.

You've cleared Chapter Three.

You've acquired S Rank in "Showdown Between Best Friends".

You can now use members of Naruto's generation.

You've acquired S Rank in "Sakura Dances".

You've cleared the Prologue.

Joined and completed a match as part of a squad

Killed another player while cloaked

Killed a player using the Exo in any multiplayer mode

Destroyed Stahl's Cruiser and left the planet on any difficulty