Into the Hunter x Hunter world with Jujutsu Kaisen System

Wing wasn't expecting to see Sachiko fighting Kastro. Since he heard from Killua that Sachiko would be on a trip, he assumed she wouldn't return before her match with Hisoka. But, he soon realized the reaason.

"I'm guessing her deadline for a fight is the reason. Since her last win was more than two months ago, she needs to register for a match before the date of her match with Hisoka." Wing shared his thoughts to Zushi who was still training with him.

"Master, are we watching the fight?" Zushi asked.

"Naturally," Wing replied before turning up the volume of the TV. "I think this would be a good chance for you to learn from a fight." 

"Osu." Zushi replied, turning his attention to the TV. 

As he also focused on the TV, Wing couldn't help but anticipate how Sachiko would fight. He had yet to find out what exactly was her nen ability and so far, he had seen her unusual endurance even without nen, and her ability to look unhinged in dangerous scenarios. He had also seen her shooting out daggers and heard her explain that she used manipulation and conjuration abilities in battle.

But, Wing knew those daggers weren't her nen ability. A move achieved with manipulation nen, sure, but specialized attack? Wing knew it wasn't. 

If Sachiko was actually a Specialist, she would have one special Hatsu that didn't fit any other categories, then maybe she would develop one or two abilities with her corresponding nen types as she should still be able to master them 80%. 

To be honest, Wing was curious.

As far as knew, Sachiko was an extremely independent person who did what she wanted for her amusement. She acted freely and had the look of someone who believed in her abilities, that she could handle anything if she wanted to, be it deceiving people or just generally ruining someone's day. 

So, he wanted to see how strong she actually was. 

Wing was suprised, then scared when Sachiko used Ryu to focus 90% of her aura into defending one spot then, spreading the 10% to the rest of her body. That technique wasn't much different from Ko as the rest of her body would be pretty much vulnerable with that little amount of aura. 

"Master..."

"The technique Sachiko san is using is called Ryu. It is used to adjust the amount of aura between offensive and defensive. Normally when you use Ken, a state of maintained Ren, the offensive and defensive value is the same, if you want to focus on defending one area more or put more aura into offense in one area, you need to use Ryu." Wing explained.

"It sounds difficult.." Zushi muttered.

"Well, it is a more advanced technique than Ken and Gyo. Also, it is important to know how much aura you need to use for defending against an attack." Wing explained, "Sachiko san's Ryu right now was a form of extremely reckless application. If Kastro has hit her in any other spot than the one she was focusing her defense on, she would've been injured badly." 

But, to their surprise, Sachiko's calculation was right the first time.

As Sachiko started saying how luck was important in a battle, Wing and Zushi started to believe she was either lucky or had a nen ability that could help her in that department. 

Then, that thought was shattered when they saw her getting kicked in her back. 

"..."

"So, she wasn't 100% sure where those attacks would come." Wing muttered. 

"And yet, she still split her aura into 90% and 10%..." He shook his head. He couldn't understand why Sachiko was being that reckless. Was that also for her amusement? 

"But...Sachiko san isn't hurt?" Zushi asked. What he saw after the kick was Sachiko laughing and acting like she just hadn't been kicked by a nen infused kick. 

"How strange. Judging by the amount of aura she used to defend herself, that kick should've significantly damaged her internal organs especially since she was quite far from an Enhancer." Wing muttered. Now, that was truly peculiar. 

Just after being kicked, Wing saw Sachiko splitting her aura into 80% and 20%, which was still quite a reckless move. But remembering how little damage Sachiko had taken after the first kick, Wing started to doubt the potential damage she could suffer from Kastro.

Not long after that, Sachiko got kicked again and Wing sighed as the history repeated itself. 

Then, Sachiko revealed Kastro's nen category as an Enhancer and Wing wasn't surprised by  how Sachiko could figure it out. After all, Kastro's punches and kicks were basically revealing his strength and category as an Enhancer. 

But, the fact that Sachiko had started to predict all of Kastro's attacks made him surprised. 

"Could it be..." Wing used Gyo right away and as he expected, he saw a thin thread that was concealed by In, attached firmly to Kastro's robe. 

'I see, she most likely attached the thread to Kastro's robe in one of the two times she had been kicked. Although at the first time, she turned around and grazed the robe...' Wing thought, 'That must've been when she attached the thread.' 

"I see," Wing muttered out loud. "She has been using a thread concealed by In to track Kastro's movements. With the thread physically attached to her and Kastro's robe, she could feel every move Kastro was about to make through the sensation and movement of the thread. At the same time, Kastro had been the only one moving so much since the start of the match whereas Sachiko san stayed in pretty much same spot. She hasn't moved much, ensuring Kastro had less of a chance of finding out about the thread through sensation." 

"The thread?" Zushi asked. "I don't see it, master.."

Wing said, "Try using Gyo."

"Osu." Zushi used Gyo and after that, he saw the thread attached to Kastro's robes. "I understand now, master."

"Good," Wing nodded, "Now, the technique Sachiko san used to conceal the thread is called In, which you will learn later on. It is an advanced form of Zetsu, specializing in hiding aura rather than stopping it, making it harder to detect even for nen users. A way to counter In is to use Gyo." 

"Osu." Zushi nodded in reply. 

As they kept watching, Sachiko revealed about knowing Kastro had a double.

"Double?!" Zushi exclaimed, finding it hard to believe.

"That would make sense. It looked as if Kastro had disappeared and reappeared at another spot when he kicked her, but if Kastro had a double, then it is easy to explain." Wing said.

Wing then looked at the screen carefully and soon, Sachiko also revealed that she knew which one was the real Kastro.

With Gyo, both Wing and Zushi could now tell that Sachiko had attached a thread each to both Kastro. 

"But, master, when did she attach the thread to the double?" Zushi asked.

"She has taken two hits in total since the start of the match so it's safe to say that she attached at least one thread in those two exchanges. I'm guessing it's the first kick because she grazed Kastro's robe back then. Then, another thread could be during the second kick or when she was talking to Kastro and pointed to him. If that's the case, we can assume that in one case, Kastro used his double to land the first two kicks. And when she couldn't see the thread on the real Kastro's robe, she knew about the double. Or second case, Kastro alternated between the double and him when he kicked her two times. When she didn't see the thread on one of the two Kastro, she realized that Kastro had a double. Either way, she only touched Kastro one time so it is safe to say that her threads could be attached to remotely without needing to have direct contact with the object." Wing explained.

"That's scary....How did she find that all out and plan?.." Zushi muttered. 

"Scary indeed." Wing admitted. 

Then, to make it worse, they saw the final part where Sachiko conjured the visible version of the threads "Sticky Steel Threads" on the stage before making use of Kastro's confusion and use the invisible ones to severe his arm. 

If Wing wasn't sure before, he was now sure that Sachiko was a lot more dangerous than he initially thought. 

-------------

Hisoka wasn't expecting to see a match between Kastro and Sachiko so one could imagine his surprise when he saw the match on the TV. 

His lips curled up into a smile when he realized Sachiko successfully blocked Kastro's attack the first time when he himself couldn't find out how it worked yet. 

Then, when she got hit, she didn't take nearly as much damage he thought she would take. 

"Interesting~" Hisoka licked his lips, "You have ripened even more~" 

His hands twitch in excitement and recalling their little encounter back in Hunter Exam only made him more excited as he knew Sachiko right now was leagues better than she was back then. 

That was only confirmed when Sachiko took another hit but was still standing and laughing.

She then answered Kastro's question, saying she wasn't an Enhancer despite her great defense. 

"As expected. You're almost as big of a liar as I'm, always up for something and rarely revealing your true intentions~ It's as if you're also a Transmuter, although that wouldn't explain what you possibly had under that eyepatch.." Hisoka muttered with a knowing smile. 

Sachiko had a great defense that could take a few hits without any problems from an Enhancer like Kastro. While Kastro couldn't be said to be a real master Enhancer, it was also a fact that his punches had a considerable power. For Sachiko to block them out or not take much damage, it was safe to assume that her body was much stronger than she showed and her nen was a lot more powerful than he thought. 

"That just makes you sweeter in my eyes.." Hisoka licked his lips, turned on by the thought of how strong Sachiko could really be. 

Then, Hisoka decided to use Gyo to see a match as he sensed Sachiko was hiding something. At first, he thought Sachiko was just taking the reckless route when she splitted her aura into 90% and 10%, then 80% and 20% to defend against an opponent like Kastro who could disappear and reappear at the blind spot of the opponent. 

But, as he used Gyo, Hisoka saw that Sachiko was actually attaching a Thread concealed by In during one of the kicks she received. It was likely that when she turned around and grazed Kastro's robes after the first kick, she attached a thread to Kastro. 

Sachiko had taken advantage of her lack of aura in that spot she had just been kicked and used In the very moment she was struck. That way, many people would believe the lack of aura or the little aura was due to her uneven and reckless split in aura by using Ryu when in truth, Sachiko made use of the chance to use In and attach the thread to Kastro. 

Hisoka was also a little taken aback when he found out about Kastro's double. He guessed that how Sachiko found out about the double was because of the thread she attached to Kastro. After all, it would be a piece of cake to tell a version of Kastro wasn't attached to a thread and that would lead her to deduce that Kastro had a double. 

Hisoka was even more amused when he found that Sachiko pretended to speak with Kastro and tell him about how she knew about his nen ability and weakness. Her true goal was to attach another thread to the Kastro without the thread and make sure she could know how Kastro would attack at every moment. 

Kastro in a panicked state after his nen ability being revealed and his confidence being shaken by Sachiko's words, couldn't focus on Ren or even use Gyo to find out what Sachiko had been planning. Hisoka wasn't sure if Kastro could actually use Gyo but it didn't really matter. After all, Hisoka could see that even if he could, Kastro wouldn't be able to do anything much  with nen after wasting his memory space on an incompatible nen ability. 

Hisoka soon lost interest in Kastro completely and focused on thinking about his upcoming fight with Sachiko. The only reason he had spared Kastro was because he thought Kastro would be able to entertain him a little next time they fought. But, Hisoka was quite disappointed with what he had seen so far, it might've been a little more thrilling or amusing if he was the one fighting him instead of Sachiko.

"This works too. I got to see how much stronger she got..This is getting exciting.." Hisoka muttered. 

Hisoka had a smile on his face as he watched Sachiko made use of the visible threads to distract Kastro, then slicing his arm off with the threads concealed with In. 

What a nice little trickery she used. 

"I can't wait to break you~" Hisoka moaned excitedly as Sachiko won the match by TK0. "I'm looking forward to our match even more now."