"Special abilities?" Sarutobi Sasuke placed a hand on Satoru's shoulder and continued. "I see. Five basic chakra natures... Your arrival here really seems fated."
"What do you mean?" Satoru was deeply puzzled by the Sarutobi clan founder's words, sensing hidden meaning.
"Where were we? Right, first trial—defeat the Monkey King. The second trial requires, at minimum, mastering nature transformation for all five chakra natures," Sarutobi Sasuke said.
"At minimum?" Satoru extended his hand and looked at his palm.
In the shinobi world, mastering nature transformation for even one chakra nature made one a master, let alone five.
"Mastering five? But that's incredibly hard."
"Yes, it really is. However, as you saw, you've already beaten the Previous Monkey King. But I'm still alive. My chakra, the Monkey King's chakra, and the Nine-Tails' have merged as one. In other words, if you can't defeat me, you can't save the Previous Monkey King," Sasuke explained.
"And to beat me, one Spiral Thunder Ball won't be enough," he added. "Basic combined ninjutsu won't help you overcome me, who has mastered chakra nature transformation—not to mention beating me with the Nine-Tails' and Monkey King's chakra."
Sarutobi Sasuke himself was an elite jonin. Though the original history had no records of his battles, his victory over the Monkey King suggested his strength was at least Kage level. Factoring in the Nine-Tails' and Monkey King's chakra, Satoru estimated Sasuke's power was Super-Kage level, if not higher.
Kage levels were divided into: quasi-Kage, regular Kage, Super-Kage. Anything beyond Super-Kage was quasi-Sage of Six Paths level.
"But I already have chakra of five natures, and I can use it in battle. Doesn't that count as mastering five nature transformations?" Satoru asked.
"Ha-ha! Of course not. Everyone is born with affinity for certain chakra natures. You have five, but that has nothing to do with nature transformation. When you use Wind Release ninjutsu, it's just the technique exhibiting wind properties—not you personally applying nature transformation to create Wind," Sarutobi Sasuke drew a kunai from Satoru's tool pouch.
"You might not get it yet. Look closely at this kunai."
Satoru focused on the weapon.
"Applying Fire nature transformation," after Sasuke's words, the kunai glowed red-hot, as if imbued with fire's power.
"Now, Wind nature transformation." Instantly, wind currents coated the kunai, making it incredibly sharp, much like Asuma Sarutobi's weapons.
Satoru seemed to grasp something.
"Five basic chakra nature transformations. Mastering even one well makes you a strong warrior in that field. Mastering two and combining them creates..." Sarutobi Sasuke trailed off, but Satoru got it instantly.
"That's Kekkei Genkai. Two natures form a new release technique," Satoru said.
"Correct. I'm naturally gifted with five chakra natures and mastered all five. But I never tried combining them, so I have no Kekkei Genkai abilities," Sarutobi Sasuke said. "Wind Release and Water Release create Ice Release. But combined ninjutsu can't create a new release—it just boosts power without qualitative change."
Satoru knew Sasuke was sharing knowledge, so he listened attentively without interrupting. In a short time, he gained immense insight.
Soon, Satoru entered learning mode, asking questions while practicing.
"Using Wind Release to boost movement speed—does that count?" Satoru recalled many used this for acceleration.
"Yes, that's beginner-level Wind Release nature transformation use."
"Rasengan is shape transformation. Adding Wind Release nature transformation makes Rasen Shuriken. Thunder Ball is Lightning nature transformation, so it can combine with Rasengan's shape transformation. In other words, Spiral Thunder Ball is equivalent to Rasen Shuriken, with even greater potential!"
"If I add nature transformation to Rasengan for Rasen Shuriken, then combine it with Thunder Ball's shape transformation, what ninjutsu would that be?"
Satoru sank into deep thought, fully focused. When his chakra recovered, he began his usual training.
Sarutobi Sasuke didn't interfere, silently observing the youth.
Time flew by unnoticed. No one knew how much time passed in the ancient well. Satoru completely lost track of days.
"This kid... I just wanted him to master the five basic nature transformations, but he's already experimenting with combinations. Still, it's the first time I've seen such ninjutsu talent in a human," Sarutobi Sasuke watched Satoru with great satisfaction.
"Failure again!" Satoru failed repeatedly but started over each time. Using his "cheat" of Shadow Clones, he endlessly tested Wind and Lightning combinations.
In the original story, no Wind Release and Lightning Release combination existed because Wind suppressed Lightning, making fusion extremely difficult.
But Satoru believed if Water and Fire could create Boil Release, his Wind and Lightning could definitely create something new.
Satoru devoted himself fully to researching the new nature. Soon, he mastered Wind and Lightning nature transformations. To develop the new technique, he studied Water and Fire transformations too, mastering two more. He quickly picked up Earth nature transformation as well, but it barely concerned him now. His focus was Wind-Lightning fusion.
"Child, you're the most talented ninja I've ever seen. Even Hiruzen isn't as gifted. Don't rush—you're only six..." Sarutobi Sasuke tried to persuade him, but Satoru ignored him, obsessed with merging Wind and Lightning.
Only when Satoru finally grasped something did Sarutobi Sasuke say:
"Child, looks like you've achieved great success this time. Konoha has a worthy successor."
"This is the Sarutobi clan's ninjutsu. I didn't pass it to Hiruzen before dying. When you meet the Sarutobi descendants, teach them on my behalf."
"Good kid, you're truly strong. But I... I can't hold on anymore. Remember, you must defeat me. Only by beating me can you earn the right to learn senjutsu." Sarutobi Sasuke's tone was strange, giving Satoru a bad feeling.
"It's been years in this seal. Time for you to leave."