Flak Jacket

A flak jacket is an item of protective clothing popular among ninja. Flak jackets have several pockets and pouches that can be used to store and quickly access weapons and other supplies. When on missions, they provide at least partial protection from damage by blunt-force trauma, shrapnel, other projectiles, and even blades. Flak jackets started being worn around the time of the First Shinobi World War, replacing the plate armour common during the Warring States Period. They can be worn by ninja of every rank, but are mostly worn by chūnin rank or higher.

Styles
Each hidden village, nation, and several other armed factions has their own design or designs of flak jacket.

Trivia

 * During the Warring States Period, a member of the Hagoromo clan was seen wearing plate armour that closely resembled the later design of Kumogakure's flak jacket.