Board Thread:Theories and Speculation/@comment-5407586-20150624095943/@comment-2043993-20150624165137

Thekillman wrote: Didn't Kakuzu harden his body too?

Kakuzu's technique was called Earth Release: Earth Spear and thus not related to steel release so far as we know. The movie character Hiruko used Steel Release: Impervious Armour that has a similar effect, if that's any help.