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 his escort, to guard him along the way to the Kage Summit.

Later, he is seen walking with Danzo and Torune, and the group is attacked by assassins. Danzo tells them not to do anything, intending to fight the assailants himself.

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