|Earth Release: Earth Spear|
|Viz print media||Earth Style: Earth Spear|
|English anime||Earth Style: Iron Skin|
|Manga||Volume #35, Naruto Chapter #314|
|Anime||Naruto Shippūden Episode #73|
|Appears in||Anime, Manga|
|Classification||Ninjutsu, Chakra Flow|
The user flows chakra through all parts of their body causing it to become noticeably darker, which increases their defensive power to its utmost limits by making the skin as hard as diamond, easily capable of withstanding most attacks with little to no damage. As a result the amount of techniques that can break through the areas hardened by the Earth Spear are close to zero, excluding its undeniable weak point: Lightning Release ninjutsu. Furthermore, the destructive power of physical attacks is increased, making this a great all-purpose technique.
Kakuzu demonstrated the ability to use this to cover himself partially (i.e. his hand and lower arm, and the side of his head) without using hand seals, which gave him a significant tactical advantage against ambushes.
- Like the rest of Kakuzu's techniques, the name of this technique comes from the legendary mecha anime "Mobile Suit Gundam" (機動戦士ガンダム, Kidō Senshi Gandamu). The name Domu was taken from the Gundam MS-09 Dom (ドム, Domu). The name was given kanji to create the name of this technique.
- This technique's attribute of darkening of skin colour as a result of hardening is similar to Hiruko's Steel Release technique.