"Ninjutsu should be learned in a systematic way. So, for the next one... let's go with the upgraded version of the Shadow Clone: the Multi-Size Shadow Clone Jutsu (Massive Shadow Clone)," Kushina muttered, scratching her head as she struggled to decide what to teach next.
"Even though it's an A-rank jutsu, it's really just a reinforced version of the Shadow Clone, so the difficulty of the training shouldn't be too high."
Hagoromo shot a silent look at Kushina. He thought to himself that while the difficulty might not be high, it was a forbidden technique for a reason—it consumes tons of chakra. Besides, with his fighting style and constitution, the standard Shadow Clone was usually more than enough; he didn't really have a tactical need to spawn an army.
But since Kushina wanted to teach it, he was happy to learn. As long as he controlled his chakra output, he could avoid the inherent dangers of the technique.
The Multi-Size Shadow Clone is dangerous because it requires distributing a massive amount of chakra all at once; if the control slips, it can cause internal injury. Hagoromo, however, was confident that his precision control would prevent such a mishap.
Still, he felt the need to check. "Uh, Kushina-sensei, isn't the Multi-Size Shadow Clone a forbidden technique? Is it okay to teach it to me?"
"It is a forbidden technique, but I'm the one teaching you. Do you think the Third will have an objection?"
Hagoromo really wanted to say: Kushina-sensei, you've misunderstood me. I'm not worried about whether the Hokage permits it; I'm worried about whether this jutsu will kill me. Our concerns are in different places!
Fortunately, Kushina continued her explanation. "While it's forbidden, the restriction is mainly for ninjas below Jonin level. For someone at the Jonin level, it's not a big deal. Based on my sensory perception, your chakra volume is... passable. So it should be fine. Probably."
Wait a minute. What do you mean 'probably'? Is there still a risk?
The difference between the standard Shadow Clone and the Multi-Size version lies in the volume of chakra flowing through the meridians. If a single clone requires 1 unit of chakra, then creating three clones simultaneously requires 3 units to surge through those same pathways during the seal. If you're only making a handful of clones, it isn't too difficult or dangerous.
But if you want to create more than ten? The difficulty spikes. If you want to create hundreds or thousands... only "bugs" like the Uzumaki or Senju clans can pull that off. Hagoromo knew better than to hope for that. His chakra was great compared to an average person, but compared to an Uzumaki, he'd just end up hurting his own feelings.
"Watch closely..." Kushina demonstrated the technique once more.
Hagoromo was a man who knew his limits. When practicing the Multi-Size Shadow Clone, he never exceeded five clones at a time. Within that self-imposed limit, he mastered the technique with ease.
"Excellent, you're quite composed," Kushina praised, patting his shoulder. "Tell you what, I'll teach you one more today. It'll be the last one for now, and it's still in the clone family: Shuriken Shadow Clone Jutsu."
Isn't that a technique copyrighted by the Third Hokage? Is it really okay to throw it around so recklessly? Hagoromo had his doubts.
In truth, it would be an issue for anyone else. But for Kushina, it was no problem at all.
Kushina was actually feeling a bit flustered—not because of the Hokage's "copyright," but because of Hagoromo's learning speed. If she didn't limit him, he'd probably learn every jutsu she knew in record time. What would she do then? A teacher with nothing left to teach would be a tragedy.
Having a student like this was making Kushina feel a mix of luck and impending "doom." Still, she thought of Minato's constant praise for Kakashi. Gritting her teeth, she decided she had to keep pushing Hagoromo.
Hagoromo was perfectly satisfied. Besides Kushina, what other teacher would teach him three high-level ninjutsu in a single day?
Of course, with his current chakra reserves, he couldn't spam these high-level jutsus in battle indefinitely. But his curiosity made it impossible for him to give up the pursuit of advanced arts. To him, the more advanced a jutsu, the more mysterious and attractive it was.
And so, the routine was established: Kushina would train Hagoromo, carry out her own duties, and occasionally—to appease the Hokage's constant nagging—take Hagoromo on low-level D-rank missions like catching cats and dogs.
Time flew by. Before they knew it, three months had passed since Hagoromo's graduation. His former classmates had long since followed their team leaders to the front lines. Hagoromo suspected many had already fallen in battle, yet he hadn't even stepped foot outside Konoha's gates.
In this sense, he was performing his duty as a "toy" (or emotional anchor) for Kushina perfectly.
"Huh? Kushina-sensei, you seem really happy today. You don't have that 'the world is ending' look you've had lately," Hagoromo remarked.
For the past several days, Kushina had been irritable because her research progress had stalled. But today, her mood had suddenly cleared.
After three months of working together, Hagoromo knew her well.
"Does this mean there's been a breakthrough in the development of the Reverse Four Symbols Seal?"
That's right. Over the last three months, Hagoromo had transformed from a rookie into a professional assistant capable of helping Kushina develop S-rank forbidden techniques.
Kushina handled the design of the sealing formulas, while Hagoromo took charge of the complex data calculations. They made an excellent team.
The Reverse Four Symbols Seal was an extreme variation of the standard Four Symbols Seal. It was an S-rank task assigned by Konoha's sealing research department. The original requirement was for the jutsu to be a "suicide" move—a ninja would activate it upon death to seal away all nearby enemies.
However, Hagoromo had proposed a different perspective. He argued that restricting the seal to the human body was too narrow. If they could adapt it to be used on scrolls instead of just flesh, it could become a devastatingly offensive weapon.
Kushina found her student's idea fascinating. She also felt the original S-rank parameters were beneath her skill level, so she had set out to improve the technique according to Hagoromo's suggestion.
However, once they actually started, the true difficulty of the task revealed itself.
Consequently, Hagoromo had to deal with a lot of "frustrated Kushina" moments. Until today.