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.

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