Fū Yamanaka

is a ninja of Konohagakure, and a seemingly high-ranking member of the Foundation.

The Summit of the Five Kage arc
Fū is hand-picked by Danzo, along with Torune, as one of his unmasked escorts, to protect him during his journey to the Kage Summit in the Land of Iron.

Before departing, Fū asked Danzo about how they should prepare for the trip; Danzo told him to not worry about it and prepare in any way he sees fit.

Later, he is seen walking with Danzo and Torune, and the group is attacked by the Hanya Assassins from the Land of Wood. Danzo tells them not to do anything and brutally defeats all the assailants. When the Raikage became too violent, he and Torune, along with the other kage escorts, jumped into a defensive stance. He was told by Danzo to stand down. When White Zetsu appears during the summit, Fu and Torune guard Danzo. When him and Torune try to go and battle Sasuke they are stopped by Ao who was told to watch them  by Raikage  him and Torune try to attack but are stopped by Danzo. He later reveals to Danzo that their location has been found out by a member of Sasuke's squad, and he asks what they should do, to which Danzo replies that they stay where they are, and if attacked, they could use the confusion to escape. When Sasuke and Karin get to where the summit is taking place, Fū, along with Torune and Danzo, escape but they are chased after by Ao.

Abilities
Fū appears to be a sensor, along with Karin, Shi and Ao. He is skilled enough to detect Sasuke and Karin planned to approach them, and that Karin is a sensor type.

Fū has also been shown to possess an ability similar to the Yamanaka possession techniques, called the Spirit Switch Cursed Doll Technique, in which he transferred his consciousness into a strange scarecrow like body with what look like hoe blades for limbs and proceeded to try and fight Ao. Although seemingly easily defeated, Ao then found that a secondary skill similar to the Cursed Mark switched his perception with the scarecrow. All the while, Fū was unconscious and being carried around by Torune, much like the Yamanaka technique.

Although Fū has not been shown using any other jutsu yet, Danzo stated that he and Torune are two of the most-skilled ninja in Root.

Trivia
Because of his mind-transfer jutsu, it is possible that Fū is a member of the Yamanaka clan.