At that moment, Tsunade acknowledged the Rasengan's power.
Of course, Tsunade had no intention of learning it. To her, the Rasengan wasn't worth the trouble. A punch backed by her Monstrous Strength might hit just as hard.
She even thought Uchiha Yi had no need to develop the Rasengan. Why not just punch his enemies?
He wouldn't even need the Sword of the Thunder God. His fists could settle everything.
He could use the Flying Thunder God Technique to appear behind an enemy, then smash a fist into their spine. That would kill them outright or, at the very least, leave them paralyzed from the waist down. Who needed a Rasengan?
Still, Tsunade supported teaching Nawaki and Kushina Uzumaki the Rasengan. Not everyone was suited to using Monstrous Strength.
Training in the Rasengan would also sharpen their Chakra control. Even if the technique didn't suit them, learning Monstrous Strength later would be much easier.
"But this Rasengan isn't complete yet, is it?" Mito Uzumaki looked with satisfaction at the damage the Big Ball Rasengan had caused, though she could sense that it wasn't the technique's final form.
At the moment, Mito Uzumaki saw more promise in the Rasengan than in the Chidori.
Of course, the same Ninjutsu could produce different results in different hands.
Tsunade's Monstrous Strength, for instance, was far more powerful than Uchiha Yi's.
"Right. I can still add other Chakra natures to the Rasengan, but that's extremely difficult. I can't do it yet." Uchiha Yi thought of all the variations Naruto would create in the future and felt a surge of emotion. For now, the Rasengan was a Ninjutsu he could pair with the Flying Thunder God Technique.
The Flying Thunder God Technique and the Rasengan would become Minato Namikaze's signature combination.
Of course, Minato Namikaze had