A Terrifying Secret

Naruto arrives on the battlefield carrying the answer to a question Kakashi thought unanswerable: how to complete the Rasengan. The Wind Style: Rasenshuriken screams into existence — a jutsu so dense with chakra blades that Kakuzu's masks read it as suicide to approach. But the technique that finally outclasses an Akatsuki immortal cuts both ways, shredding the chakra pathways in Naruto's own arm. Tsunade's diagnosis lands like a sentence: the strongest weapon in Konoha's arsenal is forbidden to its wielder.