Ninjago - Samurai X

After the devastating disappearance of the world's greatest heroes, crime and villainy had festered and grown to new heights ever since their greatest threats had vanished. But five years after the incident, an old hero mysteriously returns to a crime-riddled city to take back what had been taken all those years ago.
Meanwhile, as faceless villain slowly arises from the darkness to initiate a sinister plan, a seemingly insignificant person discovers that her newly-realized significance may affect things beyond the realm itself.

As Samurai X rises from the ashes to fight an unfinished battle, they will be quick to realize that what they have come back to is of far more importance then they could have ever imagined, and that they must take desperate measures if it means keeping the city-and all of Ninjago-safe.