4th generation kage

[Rikudou Tobi]

Even Hashirama can die with a Kunai. They dont have a body like the Raikages which Minato was going to strike them with a mere kunai.

They do if not better. Yagura has the thickest considering that he's got

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. So a kunai isn't going to kill him let alone damage him. Rasa has shukaku's power and magnetic release: Gold dust. And I'm sure you're not gonna try to tell me that Gold can be pierced by a kunai.

And Minato isn't cutting through Raiton armor.