Character Use: Uzumaki Naruto, Jiraiya, Yondaime Hokage, Hatake Kakashi
Range: Close (0m ~ 5m)
Rasengan was a ninjutsu technique developed over the span of three years by the Fourth Hokage. The technique was taught to his sensei Jiraiya, who then passed it on to the young ninja Naruto years later. Like Kage Bunshin, Naruto would adopt the technique as a signature move and make it all his own. The technique is unlike other jutsu in that it does not require any handseals, it just relied on the ninja's ability to mold chakra. The ninja concentrates a contained, fast, rotating sphere of chakra in the palm of their hand which can cause much destructive impact.
Thus the technique was pure shape manipulation of chakra, unlike most elemental techniques which are shape and nature manipulation. Hatake Kakashi stated the technique was unfinished for this reason, as the Fourth Hokage did not get a chance to add some form of nature manipulation to it and it was even unclear whether it is even possible for an elemental nature to be added. Naruto dedicated himself to this task though, in the hopes of fusing his Wind elemental nature with the Rasengan's shape manipulation. He eventually succeeded after long and hard training, which took advantage of Kage Bunshin's memory absorption capabilities. He was able to finish the jutsu in the span of a few weeks what would have taken a normal ninja numerous years. The new Wind Element version was thus named Fuuton: Rasengan.
To teach Naruto the Rasengan, Jiraiya broke the training down into three parts. With a foundation of water and tree walking, Jiraiya wanted Naruto to create a flow of chakra from his palm and rotate it. By holding a water balloon in his hand, the released chakra would cause the water inside to move. The first act is to gather and maintain chakra in ones hand; this uses skills gained in the tree climbing exercise. Next the ninja needs to release a constant amount of chakra as learned in the water walking exercise. Finally the ninja needs to push and rotate the water inside the water balloon.
Jiraiya thus broke down the training into three steps. First Naruto had to rotate the water and break the water balloon; this step emphasizes rotation. The rotating chakra must spin in proper synch with the body. When the body and spirit energy mix to form chakra, it rotates clockwise or counter clockwise within the body of the ninja. The ninja will need to spin the chakra within the palm in the same direction it does in the body to attain maximum efficiency. Naruto had trouble popping the balloon with the first step, because he was unable to make his chakra rotate randomly with only one hand. To make up for this issue, he learned to utilize his right hand to release the chakra, and then use this hand to strike the left balloon hand multiple times to rotate the water inside. This caused the water to rotate multiple ways, creating enough instability to break the balloon.
The second step involves breaking a rubber ball, much like the water balloon but about 100 times more difficult to pop. This step emphasizes power. Because the ball lacks water, it is more difficult to imagine the spinning chakra inside. Naruto had the most difficulty with this step. No matter how much chakra he pumped into the ball it would not pop, causing more and more pain in his hands. He then grasped he would need to build and keep storing the chakra until he could bear the pain no more, and then begin the rotation process. Doing it in this fashion allowed him to pierce the skin and deflate the ball. This step is hard because there was little for Naruto to concentrate on. To rectify this, Jiraiya had Naruto concentrate on a mark made in the palm of the hand. Naruto had difficulty concentrating on the spot until he remembered back to the leaf forehead training his teacher Iruka taught years before. By placing a leaf to the forehead, a ninja would have to properly concentrate on it alone and mold the chakra to keep it affixed to the forehead. Naruto modified his palm mark to look like a leaf. He then focused and concentrated his chakra to this spot and the ball exploded!
The third step involves quickly rotating the chakra randomly in a balloon full of air. This causes the chakra to form a spherical shape akin to a small typhoon. Though even more power and rotation is used than in step two, the balloon itself will not move or pop due to the precise chakra control. Using 100% of the skills used in steps one and two, the ninja is to create an imaginary layer to contain the rotating chakra and compress the chakra within that layer. By retaining this power within the hand alone, the power will not disperse, it will become faster and more concentrated and reach its ultimate destructive power. Naruto had trouble controlling 100% of his power with just two hands and had to rely on a Kage Bunshin clone to help contain the rotating chakra within the spherical layer.
Mastering Normal Rasengan:
Naruto would later advance his skills, giving him greater control of his chakra during the Rasengan creation process. Naruto would also go on to further make the jutsu his own, by creating a new variation of the Rasengan called Oodama Rasengan, this "Big Ball" version relies on a Kage Bunshin, but packs an even more powerful impact than the normal Rasengan.
Creating an Elemental Rasengan:
Naruto's drive to stay on equal footing with Uchiha Sasuke would cause him to take the next step in developing the Rasengan. Upon speaking with Hatake Kakashi, Naruto realized that Kage Bunshin transfer their memeory back to the ninja upon dispersal. Because Naruto had access to vast quanities of chakra, he could use Tajuu Kage Bunshin fairly extensively. This would allow each Naruto to work on the jutsu, disperse and then give the rest the updated information. This allowed Naruto to use thousands of clones and greatly reduce the time needed to figure out how to successfully alter the nature of the chakra into his Wind element type. What would have taken Naruto alone possibly decades to do; he managed to do in the span of about a week. It is unclear whether any other elements could successfully be added to the Rasengan shaped chakra. With enough time and training, a ninja with enough control over an element type may be able to do so.
Wind Element Training Step One:
The Wind Element is known for its ability to cut and sever most anything, making it an excellent offensive oriented ability for close and mid-ranged battles. The first step in wind training is placing a leaf between ones palms and then cutting it in half with only ones chakra. To manipulate ones chakra it helps if the ninja imagines their chakra splitting into two and then grinding back across themselves. This allows the two chakra fields to essentially sharpen the other into a very thin and sharp cutting edge.
Wind Element Training Step Two:
The second step involves cutting running water with all the Wind chakra the ninja can manage. With this the ninja has to create and produce massive amounts of elemental chakra nearly instantaneously, just as they would in an actual jutsu. To successfully cut the water, the ninja must ensure their Wind chakra remains in the body long enough after molding it.
Wind Element Training Step Three:
The final step in Wind training is to spatially recompose your newly created elemental chakra. This allows the ninja to determine the strength and scope of their attack. The normal Rasengan itself is pure spatial recomposition of chakra. To combine the two is not easy, as the number of ninja who can do both simultaneously is limited. To do so requires a natural innate talent. It was this step which was too difficult even for the Fourth Hokage. The Fourth intended to add his own elemental chakra into the highly developed spatial recomposition of the Rasengan to create a Rank S or even higher rank of difficulty jutsu. This task proved very difficult for Naruto, extensively requiring Tenzou's Bijuu control powers. According to Naruto this task asked him to do two things which couldn't be done alone. To that end he decided to use two clones, one to help with Rasengan formation and the other to help in Wind element creation. This allowed him to finally master the technique, without the apparent need for other clones.