Fūjin

and his brother Raijin are the Legendary Stupid Brothers. They are strong albeit stupid ninja from an unknown village, and are currently imprisoned in Konohagakure. There they were befriended by Mizuki, who convinced them to help him escape by offering them food. Once they escaped, they fought Naruto and the members of Team 10. They were unable to beat the brothers, and it was not until Tsunade arrived and threatened to not give them any more food that they returned to jail.