Nanafushi

was a ninja who hailed from the Land of Valleys.

Lee's Dojo Arc
He was set to steal Konoha's secrets. He used the Transformation Technique to disguise himself as Might Guy. As he entered the village, Naruto thought he was the real Might Guy and took him to Rock Lee's dōjō. After a few fights he received, the real Might Guy returned and fought Nanafushi (who concealed himself as Rock Lee by using the Transformation Technique again). After they carried him to Tsunade's office, she gave them the mission to find Nanafushi, which caused some confusion since they already had him.

Trivia

 * "Nanafushi" means in Japanese.