Wind Release: Rasenshuriken

The Wind Release: Rasenshuriken was created by Naruto Uzumaki after he had mastered the Wind Release: Rasengan. By manipulating the wind chakra of the Wind Release: Rasengan, Naruto was able to create four large points, making the Rasengan appear as a giant Fūma Shuriken, with the Rasengan in the center remaining a perfect sphere. The technique also gives off a loud bell-like screech when being formed.

Effects
When the Rasenshuriken hits a target, the victim becomes trapped in a giant vortex of microscopic wind-blades that attack the body on a cellular level. It produces so many individual strikes that even Kakashi Hatake is unable to count them all with his Sharingan. The wind chakra severs the chakra and nerve channels in the body, and if the chakra circulatory system is damaged, it can't be repaired by any form of medical ninjutsu (in a manner similar to poison as stated by Tsunade).

Other than the damage done to his cells, Kakuzu's body was left intact after being struck with the initial version of the Rasenshuriken. After Naruto perfects the technique through use of senjutsu, the damage is greatly increased; not only is capable of cutting through rocky mountains, but when Pain's Human Path is struck by it, its body is ripped to shreds.

Improvement
When Naruto first begins using the Rasenshuriken, it lacks stability and is prone to dissipating before it even reaches its target. For this reason, Naruto must use it as a melee weapon and force it into the opponent, similar to any other Rasengan. That is why, to successfully use the Rasenshuriken, Naruto first needed to use his shadow clones to distract the opponent, so that he could sneak up from behind to attack them with the Rasenshuriken. However, the greatest disadvantage of the melee use of the Rasenshuriken is that it causes the damage done to the opponent to also be done to Naruto, breaking his arm and doing limited cellular damage to it after using it against Kakuzu. Through repeated use of the Rasenshuriken as it is, Naruto would be left unable to use jutsu again, prompting Tsunade to label it as a kinjutsu.

When Naruto learns Senjutsu, he encases the Rasenshuriken in sage chakra to maintain its shape. This allows him to throw it at his opponents, removing the possibility of it damaging himself. He is also able to expand it after it has been thrown, compensating for imprecise aim or fleeing opponents by widening the area of effect. The senjutsu chakra also allows Naruto to increase the Rasenshuriken's destructive power, as the technique that left Kakuzu's body reasonably intact has improved to the point of tearing Pain's Human Path to pieces. When fighting Pain's Deva Path, Naruto has also combined the Rasenshuriken with the Shadow Shuriken Technique, throwing two Rasenshuriken, one hidden behind the other to catch his opponent off guard.

Under his own power, Naruto is left very fatigued after use of the Rasenshuriken, due to it needing great deals of chakra to be performed. While in Sage Mode, he can use it twice, in addition to a Rasenrengan. He then must re-enter Sage Mode to restore his number of uses of the Rasenshuriken.

Other Media

 * In Japan, there is an inflatable Rasenshuriken released as a cosplay toy.

Trivia

 * In the second Naruto artbook and in the third databook, when Naruto is in his initial jinchūriki form, the Rasenshuriken is colored red. Masashi Kishimoto notes this to be because, like the Rasengan, he had yet to decide upon a color for the jutsu. However as of the color cover of chapter 453, it is blueish white.
 * In Naruto Shippūden 3: Inheritors of the Will of Fire, Hiruko tries to absorb this technique, but is unable to combine the shape and nature transformation, like Naruto did at first. The sphere begins forming in his hand, but it becomes unstable and disperses.