Ryūgakure.

Ryūgakure is the hidden village of Ryūchi cave and was founded by the First Shikage (Uchiha Raijin). Even though the village is not one of the Five Great Shinobi Countries, Ryūgakure has a Kage as its leader known as the Shikage. A large number of shinobi from this village seem to have an affinity for Senninka, which allows them to passively absorb natural energy, resulting in increased physical abilities and the possibility to perform various shape-shifting feats, and gives them the ability to manipulate their own skeletal structure. By infusing their calcium with chakra, they could manipulate the growth and properties of their bones to their liking. This transformation is a multifaceted ability that permits them to achieve feats ranging from creating various weapon-like appendages to even consuming other human beings, as well as a general increase in their physical capabilities.

Attire
Ryūgakure ANBU flak jackets are white; they are a rather utilitarian version with no scroll pouches and are fastened by only one strap over the left shoulder. The strap is attached via a button and the jacket has a strange design on the front which consists of one diagonal line going down to the left with four small lines on top and one medium size line going down to the right that is perpendicular the previous line. And while the flak jacket only covers half of the torso, this is compensated with the use of shin and arm guards.

Ryūgakure flak jackets are black. For protection, they come with shoulder padding (which is fastened on by steel buttons) and a neck guard. They are also fastened by three metal clasps on the left side and have a pouch in the front just over the stomach.