Twelve Guardian Ninja

The were a group of twelve elite warriors who had left their village and had pledged their lives to protect the Fire Daimyō. The members are identified by the kanji for marked on the waist-sashes they wear.

History
A group which was formed before the start of the story, the Twelve Guardian Ninja have for a long time protected the daimyō. All the original members are dead, but the group continues to operate. About two years after the Nine-Tails' Attack on Konoha, half of the original members began to believe that only the daimyō should lead the Land of Fire. To that end they planned a coup d'etat against the Hokage, and planned to later conquer the rest of the countries. Kazuma tried to remove the daimyō to replace him with a puppet daimyō, as the current daimyō didn't support the revolt, but he was stopped by Asuma before he could do so. The different ideals split the group in two, which led to a fight between them that only Asuma Sarutobi, Kazuma, and Chiriku survived. It would seem that, sometime before the group was disbanded, some underground organisation put a bounty on most of the members' heads.

In the anime, Kazuma tried once again to destroy the Hokage and Konoha by resurrecting the four fallen loyal guardians. However, Asuma was able to stop and kill him. Chiriku was killed soon afterwards by Hidan and Kakuzu of Akatsuki, in order to collect the bounty on his head. Once they had collected the 30 million ryō they were confronted by Asuma. After a prolonged battle, Asuma was killed too, but they were unable to cash-in on his 35 million bounty after Asuma's reinforcements arrived.

Trivia

 * Shikamaru Nara received an invitation from the daimyō of the Land of Fire to become one of his guards, which could have led to later becoming a member of the elite Twelve Guardian Ninja. He refused however, saying that he would rather stay in Konoha and protect his friends.