Steel Release

The is a specialised nature transformation kekkei genkai that can be used to make one's body virtually indestructible by turning it into black steel. It is unknown what elements this nature entails.

In Naruto Shippūden the Movie: The Will of Fire, Hiruko obtained this nature by using his Chimera Technique to steal kekkei genkai from an unknown shinobi.

Kouton - Stahl pt-br:Liberação de Aço Elemen Baja