The Rasengan (Spiralling Sphere) is an A-rank ninjutsu and one with the highest possible level of shape transformation.

It releases chakra from the palm of the ninja’s hand which spins wildly in all directions at once and is compressed into the shape of a sphere. The chakra swirls like a typhoon but stably maintains its rotation and power, creating the equivalent of a hurricane in one’s hand.

Once the ninja strikes their enemy, the compressed force of the rotation is released and its destructive power is amplified. It grinds into the target’s body and releases a spiralling shockwave of force into and beyond them to sweep away everything in its path and overturn the earth as it blasts them back.

The amount of force the Rasengan can unleash depends on the number and speed of the chakra’s rotation, the amount of chakra it contains and how stable the compression is. The more it spins, the faster it spins and the more chakra released then the greater it becomes in size and power. The less chakra the user possesses and/or the less control they have then the smaller and weaker their Rasengan would be.

The exact effect that the Rasengan has on its target can be controlled by the caster to a degree. It can expend all of its energies into grinding away at the target instead of exploding, or the rotation can be weakened to avoid internal damage and only throw them back with the force of the explosion. The effects also vary between human and non-human targets as the former receive lethal internal damage but remain intact while the latter is usually blown apart as they are able unable to withstand it.

Creation and Development

It was invented by the Fourth Hokage, Namikaze Minato, when he was inspired by witnessing the Tailed Beast Ball during his clashes with Kumo’s A-B Combo. In their battles, he analyzed how the jutsu worked and believed that he could recreate that process with his own chakra.

It took him three years of experimenting with chakra manipulation to create the Rasengan (or the Spiralling Ultra Hurricane Human Beast Ball as it was originally going to be named).

Usually one would develop a jutsu by imagining the desired result, developing theories on what kind of chakra transformation it would require and then experimenting with the possible hand-seal combination to achieve that result. But because the entire jutsu was based on something created by a Tailed Beast who never used hand-seals and were innately capable of compressing their chakra, he decided it would be best to copy it as accurately with pure chakra control.

For that purpose, he broke the entire process down into three stages achieved through three lessons. The first stage is to release chakra from the hand and make it spin widly, the second stage is to increase the power being used to its limit and the third is to compress the greatest force of the rotation.

The first lesson is to burst a water balloon with chakra by causing the water to spin wildly in multiple directions. The more directions it spins and the greater the speed then the greater the rotation. The second lesson is to burst a rubber ball by increasing the force of the chakra to its maximum. This places a great burden on the chakra pathways of the body due to the high level of chakra focused in one region. And the third lesson is to compress the greatest force of the rotation to maintain a stable sphere.

Once Minato had completed the Rasengan it was, at first, merely capable of sending an enemy flying with its power. But after six months of continual practice he was able to get his Rasengan to the peak of its destructive potential which could tear apart a human’s insides and blasts them away.

Naruto followed in his footsteps under his new teacher Jiraiya’s instructions. At the time he lacked the focus and control needed to master it through the traditional methods. So he came up with more unorthodox means such as using his other hand to force the chakra to swirl for the first step, and then using a shadow clone to compress and concentrate the chakra he emits. Nevertheless he was able to wield a functional Rasengan with around four and a half weeks of training.

Adding Nature Transformation

The Rasengan itself was only ever half finished.

From the very beginning, Minato had intended to combine the jutsu with nature transformation. By adding nature transformation to the pinnacle of shape transformation, he meant to create one of the most advanced and powerful ninjutsu possible.

But adding nature transformation to the Rasengan is a feat which requires a level of focus and control that would take years of devoted effort to achieve even after mastering nature transformation and the Rasengan itself.

The difficulty of trying to apply nature transformation to the already advanced chakra manipulation of the Rasengan typically causes a violent rejection between them. But when the Rasengan successfully begins that transformation, its shape starts to change to reflect the element and its power immediately surpasses the original jutsu. However this is no different than an incomplete Rasengan which holds only a fraction of its true potential. The further the transformation is taken then the more powerful its effect until it is reaches completion and the jutsu fully realizes that potential.

Minato died before he could see its completion and no-one he taught the Rasengan to was able to accomplish it when they tried either. It wasn’t until his son, Uzumaki Naruto, tried to follow in their footsteps that the Rasengan was finally completed. Naruto’s solution was to use another shadow clone to add his nature transformed chakra to the Rasengan, dividing the chakra creation, shape transformation and nature transformation between three people to reduce the amount of effort and concentration each one needs.

It took years of training before he could wield it as easily as the Rasengan itself.

Wind Release – Combining the Rasengan with wind natured chakra creates a swirling orb of chakra surrounded by four blades of wind like a shuriken. When unleashed on the target, it releases countless wind blades to tear apart their body and pulverizes everything else caught in its range of effect. The surrounding wind blades are able to cut through any obstacles and the jutsu can be made to explode even without hitting anything.

Lightning Release – Combining the Rasengan with lightning natured chakra creates a compressed mass of electricity. When it strikes the target, it unleashes a huge electrical discharge which burns out their entire nervous system until they are unable to function. At the same time it releases a storm of lightning that paralyzes anyone caught in its reach.

Fire Release – Combining the Rasengan with fire natured chakra creates a swirling orb of burning chakra. It burns the target’s body until they are nothing more than charred flesh and ash while scorching their surroundings in a firestorm.

Earth Release – Combining the Rasengan with earth natured chakra creates a solid mass of rock hard chakra. It petrifies the target’s body and shakes like an earthquake, shattering their body into dust and tearing apart the surrounding land.

Water Release – Combining the Rasengan with water natured chakra creates an orb on compressed, swirling water currents. It explodes out in a destructive tide that sweeps everything away under a crushing lake.

It’s even possible for more than one chakra nature or advanced chakra natures to be combined with the Rasengan.