editIron Armour Seal Camera font awesome
Tekkō Fūin
Kanji 鉄甲封印
Rōmaji Tekkō Fūin
Viz print media Tekkofuin Steel Shell Seal
English anime Steel Shell Seal
Manga Volume #44, Naruto Chapter #408
Anime Naruto Shippūden Episode #142
Movie Naruto the Movie: Blood Prison
Game Naruto Shippūden: Ultimate Ninja Storm 2
OVA Naruto Shippūden: UNSG anime cutscenes
Appears in Anime, Manga, Game, Movie
Classification Fūinjutsu
Class Supplementary

Iron Armour Seal is the fūinjutsu used by Kumogakure to seal Gyūki into its respective hosts.


The seal itself takes the form of the kanji for "iron" (, tetsu) and is usually printed somewhere on the jinchūriki's body: Killer B's right shoulder, and Blue B's chest.[1] Not much else is known about the seal, besides the fact that it was stated by B to be of lower-quality and weaker than the Four Symbols Seal, which was used to seal Kurama inside of Naruto Uzumaki.[2]


  • In the manga, the seal is depicted as being black. In the anime however, the seal is blue.
  • In the anime, the Five Elements Unseal appears to be strong enough to break the Iron Armour Seal.[1]


  1. 1.0 1.1 Naruto: Shippūden episode 318
  2. Naruto chapter 496, page 7