Rasengan (Keam2637)

The Rasengan is a spinning ball of chakra formed and held in the palm of the user's hand.

Overview
The Rasengan was created by Minato Namikaze, which he based on the Tailed Beast Ball. He spent three years creating the Rasengan, which he intended to be the highest form of shape transformation. Like many of Minato's jutsu, the Rasengan does not require hand seals to perform. Once it is formed, it also does not require any additional chakra to sustain it, which means that there is no definite limit to how long the Rasengan can be used. Though the Rasengan's shape is consistent from user to user, its size varies from only barely large enough to be noticeable to much larger than the user's hand. With greater experience with the Rasengan comes a larger size.

Jiraiya describes the Rasengan as stronger than the Chidori, a statement that Sasuke Uchiha concurs with after comparing the damage caused by the two attacks. On contact, the Rasengan grinds into its target, propels them along the Rasengan's trajectory - either away from the user or into the ground beneath them - and at some point bursts, causing severe damage at the point of contact.

Learning
The Rasengan requires extremely refined chakra control, something that very few ninja naturally possess. For this reason the Rasengan is difficult to master. In order to help others gain the necessary chakra control, learning to use the Rasengan is broken into three steps:
 * 1) Rotation - the user learns to spin their chakra in multiple directions at once. To help in this regard, users may be given a water balloon so that they can mark their progress by the churning water; this step is complete once the user is able to burst the balloon with their chakra. It is important for the user to know which direction their body naturally spins its chakra for this step.
 * 2) Power - the user must increase the volume and density of chakra they output. To help in this regard, users may be given a rubber ball: there is no water inside to help them burst the exterior and the rubber shell is thicker than a balloon's.
 * 3) Containment - the user must combine the first two steps into a contained sphere. To help in this regard, users may be given a balloon to help them visualise the intended shape; if the balloon is popped or otherwise moves, mastery is not yet achieved.

Completion of the final step is by far the most difficult. For this reason, some people tend to use shadow clones to help them with forming the Rasengan, especially in the earlier uses of the technique, with the clone's hands being used to create the shell. This gives each of them a shortcut to using the Rasengan without spending the time to fully master their chakra. Later, not only Yuuichi Uzumaki, who mastered it during the 2-year mission hiatus, can use it without any outer aids, but also Naruto Uzumaki (during the Fourth Shinobi World War), and Konohamaru (after the war).

Improvement
There are two broad methods by which the standard Rasengan's offensive potential can be increased: making the Rasengan itself bigger (as with the Big Ball Rasengan) or by using more than one Rasengan at a time (as with Spiralling Serial Spheres).

Minato created the Rasengan with the intention of combining it with his own nature, a task that initially proved too difficult for him to complete prior to receiving advice from his adoptive son, who managed to conquer the challenge after having rescued the Fifth Kazekage. The failure on Kakashi Hatake's part at combining it with his own lightning nature later caused him to invent the Chidori instead. Naruto initially struggled to combine the Rasengan with his wind nature, which he described as needing to look left and right at the same time. He was eventually able to overcome this obstacle by using a shadow clone to provide the nature transformation while he and another shadow clone formed the Rasengan, thereby creating the Wind Release: Rasengan. By further shaping the Wind Release: Rasengan, Naruto then later created the Wind Release: Rasenshuriken. Despite not having occured for now, it has been said that there are more possible results to mixing a nature transformation with the technique.

Senjutsu Influence
While in Sage Mode, the user can use a senjutsu-enhanced version known as. It is fundamentally the same as the normal version, except stronger. While in Sage Mode, users have an easier time forming larger Rasengan, such as the Ultra-Big Ball Rasengan. For Naruto, it is while using Sage Mode that he was first able to throw the Wind Release: Rasenshuriken, which he previously hadn't been unable to do because it would have sporadically lost shape.

Tailed Beast Influence
Naruto, as a jinchūriki, can use the Nine-Tails' chakra to assist in using the Rasengan. While using a version 1 cloak in Part I, he made a Rasengan without the aid of a shadow clone, using the cloak itself to contain it. Due to the Nine-Tails' influence, this Rasengan is darker in colour and much stronger. Different video games have called it, , and. After learning to use the Nine-Tails Chakra Mode in Part II, Naruto uses chakra arms in place of a shadow clone to help him create the Rasengan. Because he can manifest multiple chakra arms at once, this in turn means he can use multiple Rasengan simultaneously, such as for the Spiralling Strife Spheres.

The Nine-Tails was initially uncooperative when Naruto first started using the Nine-Tails Chakra Mode, preventing him from using the Tailed Beast Ball. As a result, he tried to create an alternative in the Tailed Beast Rasengan, but itproved to be in vain. The Nine-Tails did later agree to work with him, allowing him to use Tailed Beast Ball and thus making the Tailed Beast Rasengan unnecessary. Naruto is later given access to the other tailed beasts' chakra, whose natures he can apply to the Rasengan and its variants, as seen with the Sage Art: Magnet Release Rasengan.

Trivia

 * In various artworks seen in wallpapers or serializations, the Rasengan has also been shown to be yellow-colored, possibly for the Rasengan to look more "majestic", as once noted be Sai while drawing the jutsu in his own work.
 * In some instances, Jiraiya could be seen spewing fire onto his Rasengan, creating a technique called Fire Release: Great Flame Rasengan.