Its going to be a lot of yapping about why things happen the way he does, with logic and a lot of mind jargoning. So if you're not ready. Just skip this chapter.
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"Twins..."
That was the only thing going on inside Sukuna's head after the entire Uchiha extermination, alongside the completion of his plan.
He had suppressed his curiosity for the sake of his goals. But now, since he knew he had at least a few years of uninterrupted peace and time to grow, he wanted answers.
Answers to questions that had been burning inside him since the day he arrived here. Like why he couldn't just have an overpowered system like most transmigrated people. Or why he couldn't use chakra.
However, another question had recently clouded his mind. It was about him and Sakura. And with the sudden entry of Sasuke's sister—and more importantly, her having cursed energy—the question regarding twins had been weighing heavily on his thoughts.
Sukuna wasn't kidding when he said he didn't have time for Kiyomi. His mind was too clouded recently, feeling like he was just a breath away from uncovering the secrets he had longed to know.
He wasn't an idiot; anyone with even a basic knowledge of Jujutsu Kaisen could tell that him being a twin to Sakura was a big deal.
Twins are considered a curse in the world of Jujutsu. And this wasn't just a superstition either. There were actual physical drawbacks to being someone's twin in that universe.
One of the major ones was that potential gets divided between the twins, as the world of Jujutsu sees both twins as one person.
This means that neither twin would be able to reach their full potential while the other one is alive. They essentially hold each other back by merely existing.
A good example of this was Maki and Mai from the original series. As twins, they were handicapped. Mai had a cursed technique but small cursed energy reserves to achieve anything significant in her life.
Maki's condition was even more complicated. If she had been a victim of a normal twin curse, then she would have been the complete opposite of Mai—possessing large amounts of cursed energy but no cursed technique.
However, she was also a carrier of a Heavenly Restriction. A phenomenon in which a person or sorcerer either gets a ridiculous level of cursed energy or something related to it at the cost of their body being weak—like how Mechamaru was in the series—or has zero cursed energy in exchange for having ridiculous physical power, like Toji Fucking Zenin.
Maki was similar to Toji—ridiculous physical power to the point where calling her a watered-down Kryptonian wouldn't be that far off. At least, it wouldn't be if she didn't have a twin.
Due to the twin curse, her potential was shared with Mai. Instead of having no cursed energy like Toji, which would have made her the next Wonder Woman, she had just a tiny bit, and that held her back immensely.
So, it is safe to say that being born as a twin sucks in the JJK world. However, this wasn't the JJK world. This was the land of ninja and chakra.
Sukuna, when he first came to this world, was horrified when he found out who his twin was. Well, many people would be, seeing as it was Sakura—but trashy reasons aside, the fact that he was a twin was the real source of his desperation.
Sukuna was already capping at Kage level in the Naruto world. If he were to lose more power, then it would be better to commit suicide now. However, he found that he wasn't restricted in any way.
After going through Sukuna's memories, he had a very close understanding of his potential and limits. And Sukuna found that he didn't face any limitations from the twin curse at all.
From day one, his cursed energy was monstrous—exactly how it was supposed to be for Sukuna. As he trained, he saw visible improvements, which quickly put him into the league of Grade 1 sorcerers, and after one year of training and landing that Black Flash on Itachi, he was already Special Grade—all but in name.
"To test that out..." Sukuna extended his hand and pointed toward the same tree he had tried to cut multiple times in the past with Dismantle and failed.
Swish.
A plain, almost effortless lash tore through the tree trunk with just his thought. A single line appeared on the trunk. And then slowly, the tree slid off at an angle, plummeting down, digging into the soil, and then—like it wanted revenge on the one who ended its peaceful life—started falling toward Sukuna.
"I knew one of these days it was gonna fall on me..." Sukuna saw the coming tree with a sigh and just accepted his fate...
Boom.
The entire ground shook as the tree hit. And from the side, after a few seconds, came Sukuna walking out from the trunk like a ghost.
He had a completely nonchalant expression on his face.
"I hope you find peace knowing that you almost crushed your enemy. Be proud, tree... you have been strong... and useful to the cause." He held a five-second mourn.
'So, as I was saying... aside from establishing that Kamui is busted once again, what I wanted to check here is that I have become strong. Much stronger.
While the one-year training helped, the real game-changer was that Black Flash. It almost changed the way I use cursed energy. Landing that one punch opened my eyes in more ways than one. From gaining better efficiency over my technique to refining its output, I was able to do both.'
This was the same tree Sukuna couldn't cut down with Dismantle earlier, and now it was cut down like paper.
This entire thing tied back to the original question—that he had been getting stronger and thus, the twin curse wasn't working on him.
This exact thing made him believe that it just doesn't exist here. Makes sense. It was the Naruto world; that curse was more of a JJK thing.
However, the recent changes he had seen—especially the connection of Yin Chakra, changes in Sakura's character from the story, his estimation regarding Yin and Yang theory, which checked out thanks to the experiment he did with Sakura and healing jutsu that led him to figure out Reverse Cursed Technique—
He wasn't sure anymore.
At first, it wasn't noticeable. However, Sakura's change in character implied that something had happened.
If it were just a matter of character, he could have chalked it up to his existence. After all, children who grow up with siblings develop differently than those who don't.
However, this didn't explain how Sakura was almost as strong as him when he wasn't using his CE reinforcement. It didn't explain how a girl who was supposed to have the best chakra control in the series ended up wasting so much chakra that her puff of smoke during a clone jutsu was as big as Naruto's.
If Iruka's idea of the smoke cloud size representing the amount of wasted chakra was any indication, then Sakura clearly wasn't acting like the chakra control prodigy she was supposed to be.
Even before the extermination or any of his plans came into play, Sukuna had tested Sakura's physical capabilities out of curiosity—through games like tag and tug of war. And indeed, she was performing ridiculously well.
This only went to show that something had happened—something different. And Sukuna had every reason to believe that it had something to do with the twin curse theory, which he had earlier disregarded. After all, what else could it be?
There was always a possibility that he got all the good stuff while Sakura got the short end of the stick in this twin curse phenomenon—if it had happened at all.
But that didn't seem to be the case. Outside of her poor chakra control, he didn't sense anything strange in her. Nothing that made her weak, not in any meaningful sense. In fact, just as he'd noted, she was stronger than she had any right to be at her age—at least physically.
It wasn't just strength, either. From stamina to reflexes, her entire body felt more capable than the average person's.
This condition resembled that of a certain Heavenly Restriction user he'd seen in JJK. Both Maki and Toji had it. That would've been his go-to explanation, but Sakura could perform ninjutsu.
He couldn't, but she could.
What was he to make of that? Honestly, he had no idea—until Iruka gave him a hint.
It wasn't just that he hadn't had time to think about it before. The night of extermination was approaching fast, and he had been more focused on his plans. But now, as he began reflecting, he started seeing the connections.
The reason he gave Sakura that healing jutsu wasn't just because he knew she would become a killer medical ninja—which, of course, she would—but because, more than anything, he wanted to test a theory.
His Yin-Yang theory. And it passed with flying colors.
No one—not even Tsunade freaking Senju—could have learned that technique in one go. Good chakra control alone isn't enough to perform it.
But Sakura was able to, and combined with her performance in the clone jutsu, this led him to believe that the majority of Sakura's chakra was Yang in nature.
The same chakra type needed for healing. This conclusion came from what he knew of Hashirama Senju. That man was a walking medical cheat code.
His chakra alone could heal others—that's how strong the Yang component of his chakra was.
Sukuna reached this conclusion after noticing parallels between Naruto and Sakura. Both had similar performances in clone jutsu—excessive smoke, as Iruka had described, indicating chakra wastage.
It was obvious to any Naruto fan that Naruto had a massive chakra reserve. But what many didn't know was that the majority of Naruto's chakra was Yang in nature. And that's aside from the Yang half of Kurama he possessed.
This was the result of his Uzumaki heritage and another chakra source inside him that came directly from ninja Zesus himself—
Ashura.
A wild idea sparked in his mind—that something akin to the twin curse had indeed occurred. But instead of dividing cursed energy like it was between Maki and Mai, the chakra was split between them.
"The idea is simple… since I don't sense any limitations on my potential outside of being unable to use chakra, and Sakura appears perfectly fine—if we don't count her excess Yang chakra and probable lack of Yin chakra…
Then the so-called limitation of the twin curse doesn't apply to us—or at least it isn't directly tied to our souls.
If it were, the limitations wouldn't stop at chakra and Yin-Yang balance. Our entire potential would've been divided. I might never have figured out Reverse Cursed Energy, let alone land something like a Black Flash.
And considering Sakura's academy performance—if we disregard the scores—and her physical strength, plus how quickly she picked up the healing technique, I don't think she's handicapped either."
So ultimately, it boiled down to the limitations placed on them from birth. His lack of chakra. Her excess Yang chakra. And her probable lack of Yin.
In this case, Sukuna had a solid theory about what might have really happened.
After his testing, he had concluded that Cursed Energy worked almost exactly like Yin chakra. Whether they were the same energy or simply resembled each other closely enough to be interchangeable was unknown to him.
Using that, combined with the results from observing and testing Sakura's chakra affinity, Sukuna finally came to the conclusion that something akin to a Heavenly Restriction or a Twin Curse power division had indeed occurred at their birth. However, instead of the chakra being naturally divided, it was split into Yin and Yang.
He ended up with the majority of the Yin chakra—which worked as Cursed Energy for him—while Sakura got the bulk of the Yang chakra.
That was the closest explanation he could find to justify their current condition. It explained his ridiculous levels of Cursed Energy and also drew further parallels to the original Ryomen Sukuna—who, by the way, supposedly killed his twin in the womb to gain his power.
Yeah, not many people know that. Sukuna had a twin—and he killed him while still in his mother's womb. That's why he was born deformed.
Four arms, four eyes, two mouths, cannibalistic tendencies, and a technique themed around cooking.
Of course, this Sukuna didn't kill Sakura. And he was mostly glad about that. However, in terms of the jujutsu world, he technically had—since he took away all the Yin energy, aka Cursed Energy, from her.
And in jujutsu terms, anything that doesn't have Cursed Energy is treated as an inanimate object—not a living being. That's what made Toji Zenin such an anomaly. The dude was born different.
'Ahem. Back to the topic…'
Sukuna wasn't sure whether this Yin and Yang division occurred because he took all of Sakura's Yin energy and turned it into Cursed Energy, or if it was part of the twins' power distribution.
He didn't even know if Sakura's enhanced physical strength and high Yang energy came from her receiving all the Yang chakra—which in turn made her body strong—or if it was a Heavenly Restriction that made her body strong, thereby increasing her Yang reserves since Yang energy originates from the physical body.
He wasn't sure. But his Yin-Yang division theory, at the very least, held weight up to this point.
There were a few caveats, though—like how Sakura could still use ninjutsu of any kind. Just like him, she shouldn't have been able to perform any jutsu with only Yang energy.
However, there were possible answers to that. Yin is a spiritual energy, and it can be cultivated again as a person matures and trains. Unlike Cursed Energy, chakra isn't entirely determined by birth.
Through effort, a shinobi can increase their reserves. Sorcerers, on the other hand, must work with the same amount of Cursed Energy they're born with.
The only way to get more "blue" is to use less of it—to be more efficient, refine technique, and sharpen skill.
According to him, Sakura could use chakra because Yin was slowly rebuilding inside her as she grew. It would still be a small amount. She'd never be able to handle powerful genjutsu with that pitiful amount of Yin chakra, if she ever hoped to in the future. But it was still enough for her to use basic jutsu.
That was something Sukuna himself couldn't say, sadly.
"Would she be like Maki or Toji if she didn't have that little bit of Yin…?" Sukuna pondered.
And honestly, the answer was probably no.
Ultimately, he believed that the concept of different power systems applied here. They both operated using different energy systems.
And if that were indeed the case, then the theory of Sakura receiving all the Yang chakra—which made her body stronger—made more sense than the idea of her getting a Heavenly Restriction like Maki, which in turn made her body strong and increased her Yang capacity.
"Sigh... what does it matter anyway," Sukuna muttered as he started to develop a headache.
This was the love-and-hate part of his journey. Figuring out his condition gave him insights that made him stronger—like how, after seeing Sakura perform healing jutsu so effortlessly, he realized that since her chakra was mostly Yang, his own must be closer to Yin. That revelation had led to the entire Yin and Yang theory, which further helped him understand the nature of his cursed energy. This understanding had enabled him to reverse its nature and learn Reverse Cursed Technique (RCT).
However, at the same time, it was just so exhausting—like beating his head against a wall—trying to make sense of any of this.
"I still need to check whether I even have a chakra network to be sure about this whole two-power-system idea," he muttered with a huff.
He had long suspected that he simply lacked the chakra network every other shinobi in this world possessed—one that allowed them to mould and manipulate chakra. He had a hell of a time learning tree walking and water walking.
If Yin chakra and cursed energy were truly the same, that shouldn't have been the case. This only supported the theory that he lacked the tool needed to manipulate his cursed energy the way shinobi manipulated chakra.
It also made sense why he was so resistant to Genjutsu. Even Itachi's Tsukuyomi had felt like a light tug on his mind before the technique collapsed entirely. After all, if he himself had difficulty manipulating his cursed energy, then it would take someone truly monstrous to manipulate it from the outside.
'So there were some upsides to this whole "not having chakra" thing after all...' he mused.
Of course, this could very well be because his energy pool was made entirely of cursed energy—which resembled Yin chakra, the very substance used to cast Genjutsu. So, it made sense that it would be harder to pull off Genjutsu on someone with an abundance of it.
Another reason could be that he'd also had the Mangekyō Sharingan active at the time.
Or maybe it was all of the above.
"I need a Hyūga to verify this chakra network theory of mine. That would answer a lot of my doubts."
From the origin of the cursed twin dynamic—or Heavenly Restriction—between him and Sakura, to the question of his future direction—whether he should continue pursuing ninjutsu or just give it up entirely—it all depended on this.
"Seems like I'll need to pay Hinata a visit soon..." he said with a slight smile.
And when it came to girls, his mind drifted back to Kiyomi.
"Was she like me...? Did this whole Yin-Yang mess happen between her and Sasuke too?" Sukuna wondered.
From the limited observations he'd made, there were definitely signs of some changes in Sasuke. He couldn't say anything for sure about Kiyomi, though.
He hadn't even known she existed until two days ago.
"Okay. A visit to two girls is in order..."
"Though, that's after I do a little testing with my new toy here..." he grinned, allowing cursed energy to flood into his Sharingan as he vanished from the spot.
Another reason he had little time nowadays was that he'd recently figured out how to solve the Mangekyō Sharingan's eyesight deterioration problem. He was in the middle of testing the solution, as well as training in Kamui.
As for how he solved the issue—that was another mind-boggling stunt he had to pull.
But more on that later.
xxx
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