Fū Yamanaka

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

Abilities
Danzō stated that he and Torune are two of the most-skilled ninja in Root. Fū also appears to be a sensor. He is skilled enough to detect Sasuke and Karin planned to approach them, and that Karin is a sensor type. His reflexes are fast enough that when Madara Uchiha reappeared he instantly sensed him and counterattacked.

Fū is also an expert in trap making. He regularly uses this skill with a cursed seal variant of the Yamanaka clan's Mind Body Switch Technique, which he transferred his consciousness into a strange scarecrow like body with kama for limbs. He proceeded to use the scarecrow to attack Ao. Although seemingly easily defeated, Ao then found that a secondary ability similar to the Cursed Seal had triggered a switch of his consciousness with the scarecrow. All the while, Fū was unconscious and being carried around by Torune, much like the Yamanaka technique.

Five Kage Summit arc
Danzō selects Fū and Torune to escort him to the Kage Summit in the Land of Iron. Once they arrive and the meeting begins, Fū comes to Danzō's defense during the Fourth Raikage's outburst and Zetsu's appearance. Zetsu informs them of Sasuke Uchiha's presence, and Fū and Torune try to go and eliminate them. The Raikage goes instead, so they stay with Danzō. Fū alerts Danzō when Sasuke's sensor locates them and subsequently flees with Danzō when Sasuke arrives at their location. They are pursued by Ao.

Danzō instructs Fū to stop Ao and safely retrieve his Byakugan. Fū lays several traps, including the Mind Puppet Switch Cursed Seal Technique, and once it activates he gains control of Ao's body. Ao's Byakugan, however, is protected with a seal that he cannot remove. Fū decides to just decapitate Ao instead so that he can take his head, but the Fifth Mizukage arrives before he can do so. Acting as Ao, Fū tries to convince her to remove the seal. The Mizukage, perfectly aware that Ao would never ask her to do this, beats up Ao to release him from Fū's control, unaware that Fū has already left.

Nearing Konoha, Fū, Torune, and Danzō are ambushed by Madara Uchiha. While Danzō prepares for battle he has Fū and Torune distract Madara. Fū tries to use the Mind Body Switch Technique, but Madara teleports away before it can connect. Madara stages a counterattack and Fū slashes at him with his sword, but Madara catches the blade. Torune throws a kunai at Madara, forcing him to release Fū. Fū and Torune try attacking from different angles, hoping that one of them will be able to attack Madara while Madara is attacking the other. Madara sees through their plan but plays along, causing Torune to accidentally infect Fū with his Poisonous Nano Bugs Technique. Torune cures him, but Madara quickly sends them both away with his space-time technique.