Rasengan

"So that's how it is. You know quite a lot. Don't get cocky—the difficulty only truly begins with the Third Stage!" The chakra sphere in Jiraiya's hand shook violently. Blue chakra splashed like water, seeming ready to spill over at any moment, yet under his control, it returned to its original position again and again.

"For the Third Stage, you'll need a ball a hundred times sturdier than a balloon. I call this Balloon Practice. Maintain the chakra you release and solidify it until you can burst the ball." Jiraiya pressed the incomplete Rasengan, which was shifting chaotically in his hand, against a nearby tree, leaving a deep mark in the trunk.

"Once you complete this stage, the Rasengan will be capable of causing damage, though only relatively light surface damage. It won't be able to pierce through a tree." Jiraiya stopped and said to Duke, who had begun training, "The difficulty of this stage rises sharply. You definitely won't succeed overnight."

Duke gave it a try, and it was just as Jiraiya had said. Compressing chakra to an extreme degree and making it spin violently produced centrifugal force that was incredibly difficult to control. Moreover, the chakra did not flow in just one direction, which undoubtedly made it far more difficult.

"This stage requires a great deal of practice. Although your chakra control is strong, this is no longer a matter of talent. It requires accumulation."

Duke did not answer, instead proving with his actions that he disagreed. In the original story, Naruto had not spent much time practicing the even more difficult Wind Release Rasengan. If Naruto could do it, so could he.

What was Nicholas Naruto's secret to success? The answer was numbers. With insufficient chakra control, Naruto would normally have needed ten years to master this jutsu, but he had forcibly piled up his very first S-rank ninjutsu through sheer numbers.

Many hands made light work; strength could work miracles!

Duke only knew the Shadow Clone Jutsu. He could not create clone after clone like Naruto. After making twenty Shadow Clones in one go, he began training with great enthusiasm.

"Young people really are full of energy!" Jiraiya laughed loudly, then leaped to one side and began instructing the various clones.

"No wonder Senior Zixiao suspected he was a descendant of the Uzumaki Clan. Ordinary shinobi couldn't withstand creating so many Shadow Clones at once," Minato said with a nod.

"Then you're underestimating the Uzumaki Bloodline too much." Kushina was noncommittal. If he truly were from the Uzumaki Clan, the number of clones would at least be in the triple digits.

"I saw it clearly. He isn't using the Multiple Shadow Clone Jutsu. Being able to create so many clones under these circumstances is already quite impressive."

"I see. Then we'll use this to judge him!" After thinking for a while, Kushina nodded happily, having come up with a good idea. Through their several encounters, she had not found any traces of Uzumaki Bloodline in Duke. The enormous chakra Duke took such pride in was nothing special in her eyes—merely ordinary. Kushina was very disappointed by this. After Uzumaki Mito's death, as Konoha's only remaining holder of the Uzumaki Bloodline, Kushina was unwilling to accept it. She longed desperately to see one of her clansmen.

"Yo!" Kushina suddenly appeared behind Duke and greeted him loudly.

"Senior Kushina, is something the matter?" Duke, who had been fully focused on studying the Rasengan, jumped in fright. The unfinished chakra in his hand dispersed along with his surprise.

"Hey, don't keep calling me Senior, Senior. You'll make me sound old. If you're willing to call me Sister Kushina, I have a very powerful ninjutsu I can teach you. Consider it a greeting gift from your big sister." Kushina smiled with narrowed eyes, rubbing her chin as she inspected Duke with ill intent.

Kushina's malicious expression gave Duke an ominous feeling. He often looked at Hades the same way, and the long-suffering Hades would immediately tuck his tail and disappear. Duke considered whether he should learn from Hades and make a strategic retreat.

"What, would calling me Sister put you at such a disadvantage?" Kushina saw that Duke was planning to slip away. She slapped a hand onto his shoulder and leaned her face closer, her red hair showing signs of transforming into tentacles again.

"How could that be? I was just... too excited. To have a well-read, sensible, young, beautiful, gentle, and kind Senior Kushina as my sister... I'm so happy." Sweat covered Duke's forehead as he hurriedly flattered her. In truth, Duke had always kept his distance from female shinobi like Kushina, who had special identities, fiery tempers, and knew how to stir things up. He did not intend to get too close, because people like that usually meant trouble.

"Not bad. I didn't expect you to have such good taste!" Kushina planted her hands on her hips, wearing an expression that said everyone already knew this, and openly accepted Duke's flattery.

"..." Jiraiya, who was instructing the clones nearby, was covered in black lines. He pretended he had heard nothing.

"But forget about the ninjutsu. Sister Kushina's ninjutsu must be the really powerful kind, and I'm afraid I won't be able to learn it. Besides, didn't you already treat me to ramen as a greeting gift?" Duke said with a dry laugh.

"That was a greeting gift from a senior, so it can't be compared. Don't worry, it's a very ordinary ninjutsu. Even an idiot can learn it." Kushina forcefully patted Duke's shoulder, clearly conveying that she would lose her temper if he dared refuse.

"..." If he learned it, he was an idiot. If he could not learn it, he was worse than an idiot. Should he learn it or not? Shakespeare had said, To be or not to be, that is the question. It was a profound question. Duke was speechless. He wanted to argue, but circumstances were stronger than him, so he could only accept it.

"Watch carefully. This ninjutsu is called the Multiple Shadow Clone Jutsu!" Kushina explained the key points of the technique in detail. "As the name suggests, this is an enhanced version of the Shadow Clone Jutsu. It can create many Shadow Clones at once. The number depends on your chakra. Theoretically, there is no upper limit. It suits a shinobi with enormous chakra like you very well. Since you know that Shadow Clones can send information back, you should understand what this jutsu means for you. Use it well."

"Thank you, Sister Kushina." Duke thanked her while lamenting inwardly that he was not even Naruto on a cellular level. Before you were even born, your mother had already defined you as an idiot... though she was not wrong.

"Alright, practice to your heart's content." After explaining the details and precautions of the Shadow Clone Jutsu, Kushina returned to Minato's side. The two of them were deeply affectionate and began shamelessly flaunting their romance again.

Duke recalled his previous Shadow Clones, circulated the chakra throughout his body, and used the Shadow Clone Jutsu for the first time. This jutsu had been invented by some idiot Second Hokage and carried forward by some idiot Seventh Hokage... Yeah, Kushina was right. Nothing wrong with that.

"Multiple Shadow Clone Jutsu!"

Poof!

The white smoke dispersed, revealing more than a hundred identical Shadow Clones on the field. The visual effect was extremely shocking. No wonder many powerful shinobi struggled to display even one hundred percent of their strength when facing Naruto, as though they had been struck by a stupidity aura.

"Everyone, begin!"

"Yeah!"

More than a hundred clones began training in the Third Stage of the Rasengan. The human-wave tactic truly deserved its reputation as the ultimate weapon that had allowed the fighting nation to defeat the Third Reich. In less than ten minutes, one clone succeeded. After recalling all the Shadow Clones, Duke obtained the technique as well.

Duke shook his head, feeling a little dizzy, but that was all. With the boosts from multiple worlds, especially the enhancement brought by Soul Society, his soul and spiritual power had become terrifyingly strong. He quickly sorted out the disorienting flood of memories and was as lively as though nothing had happened.

Having successfully mastered the Third Stage, Duke planned to strike while the iron was hot. He hurried before Jiraiya and humbly asked about the next step of the Rasengan.

Kushina and Minato watched this scene. After exchanging glances, Kushina became so excited that her body trembled slightly. There were many shinobi capable of using the Multiple Shadow Clone Jutsu, but after creating more than a hundred clones, only members of the Uzumaki Clan—whose chakra and life force stood above the Shinobi World—could endure the information and fatigue fed back by the clones.

Jiraiya saw this as well and immediately understood the deeper reason Minato and Kushina had kept Duke close: the Uzumaki Bloodline. It reminded him of his red-haired disciple Nagato from the Land of Rain, who was also a member of the Uzumaki Clan and possessed the Sage of Six Paths' Rinnegan. He was destined to be the Child of Prophecy who would change the Shinobi World.

Thinking of this, Jiraiya's fondness extended to Duke, and he began to look forward to him as well. He stared intently at Duke for nearly ten seconds before saying in a solemn tone, "You possess enormous chakra and exceptional physical ability. Combined with the Multiple Shadow Clone Jutsu Kushina taught you, you could say that you learn any ninjutsu quickly. Before I teach you the Rasengan, I have a question for you. What do you think a shinobi is?"

Hearing this, Duke frowned and did not answer. He thought seriously. In truth, he strongly agreed with Snake Uncle's words: a shinobi was someone who mastered every ninjutsu. But he absolutely could not say that aloud. First, he did not want to be regarded as the next Snake Uncle because of those words. Although Snake Uncle was still Jiraiya's close friend now, he would become utterly unscrupulous in the future, and those words would bring Duke much trouble. Second, the Hokage World had proven many times that only shinobi with strong hearts could become the strongest. Shinobi without conviction would forever be weak... For this, one only needed to look at Naruto's Talk no Jutsu.

"A shinobi is someone who can endure everything! I hope you remember that. Do you understand?" Seeing Duke remain silent in thought for so long, Jiraiya felt he might have gone too far. This question was too profound for a seven- or eight-year-old child.

"Perseverance?" Duke asked thoughtfully.

"That's right, exactly!" Jiraiya broke into a broad smile and gave him a thumbs-up in praise.

Duke nodded. The white-haired uncle before him had spent his entire life embodying the meaning of a shinobi. His lecherous and unreliable behavior could not conceal the radiant soul within him. He was a great shinobi worthy of everyone's respect.

"Then next, we'll proceed to the final stage of the Rasengan." Enjoying the sense of accomplishment that came with being a teacher, Jiraiya was greatly encouraged. His own ninja way became even firmer as he began the final lesson. "For the final stage, combine the previous three stages. Condense and release chakra, gather it in your hand and continuously release it, maintain it, then finally solidify it. Like the Third Stage, this stage requires a great deal of practice."