The Rasengan was modeled after the Tailed Beast Bomb. The Rasengan is heavy. If i don't use both of my hands it will just fall apart.
The Rasengan has been shown to be a very powerful technique even in its basic stage as seen when Naruto was able to make a much bigger impact than Sasuke's own Chidori. It can even smash through rocks like nothing due to the constant spin. He was able to make Sasuke very jealous when he saw that it surpassed his own technique the Chidori.
If that really were the case, I wouldn't have had to develop the Chidori. I was never able to combine the Rasengan change in form with the change in chakra nature to lightning. Combining a change in nature with the change in form takes incredible skill. Or I should say, it takes a great deal of natural skill and intuition. And I'm not the only one who failed at it. Even my teacher, the one who invented this jutsu, failed as well. What? That's right. Even the fourth hokage couldn't master it. The fourth hokage developed and honed the change in chakra form to its highest degree. The result being the Rasengan. Just mastering a change in form has an A-rank level of difficulty. But I can still manage to copy it. The problem comes, however, in the next step. From the moment he invented the Rasengan, it was always the fourth hokage's intention to eventually add his own change in nature to it. Hold on. Are you saying that the Rasengan is an incomplete jutsu? It is true, in a way. The jutsu we're aiming for has an S-rank level of difficulty. Possibly even beyond that. For all we know, it might even be unachievable. So, from here on, there's nothing you can be taught. You have to discover it yourself. Now, do you understand why I'm telling you all this, Naruto? It's because I truly believe that you are the only shinobi who can surpass the fourth hokage.
Now each team of two will form the Rasengan at the same time. Try incorporating the Wind change in chakra nature into it.
- According to Konohamaru the only people that can use the Rasengan were the late 4th Hokage Minato Namikaze, and old man Master Jiraiya. And among the living are only big brother Naruto Uzumaki, and myself.
- Konohamaru doesn't know that Kakashi can use the Rasengan as well.