Into the Hunter x Hunter world with Jujutsu Kaisen System

43- Fight with Kastro

The next morning, Sachiko woke up with Satoru's arms wrapped around her body. As she shifted in the bed, Satoru seemed to have woken up and opened his eyes. He wasn't wearing his glasses when he slept so Sachiko could clearly see his mesmerizing blue eyes.

"Morning. How was your sleep?" Satoru said with a chuckle. 

"Morning.." Sachiko replied. "You have to go back to Tokyo today?" 

"Yeah, I have an oversea trip." Satoru replied, "Wish we could've grabbed dinner together." 

"At least, we can grab a breakfast." Sachiko said.

Satoru chuckled, "That's true, alright, let's go grab breakfast then." 

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

After breakfast, Satoru went back to Tokyo. Of course, he didn't forget to say, "Hit me up when you get to Tokyo, will you?" 

"Sure, if I end up coming to Tokyo." Sachiko replied.

Satoru grinned, "Alright, then I'll see you later, sweetcheeks." 

"Mn, see you later, Satoru." 

After that, Sachiko went back to the hospital to check on the residuals but as Satoru said, there were no residuals left after the incident so it was practically impossible to track the source or culprit of the second barrier. 

However, Sachiko expected this. 

If something or someone was powerful enough to pull this off, she knew it wouldn't be easy to track them down. 

So, Sachiko decided to not worry too much for now and just focus on her regular training and nen abilities while waiting for an opportunity. 

She spent the rest of the week practicing Time Manipulation Eyes on the side and worked on familiarizing her aura with Carbon monoxide and flammable, poisonous gasses. 

"At this rate, I should be able to transmute my aura into a gas that has properties of Carbon monoxide and extremely flammable gas in a month. After that, I can start working on manipulation nen." Sachiko muttered. 

"But, I'd prefer to have those two nen abilities to be a secret." After all, her aura having the properties of Carbon monoxide and flammable gases could lose its advantage once it became widely known.

Although it was harder to guard against the nature of Carbon monoxide in a battle than normal poisons, losing the element of surprise meant quite a disadvantage. Not to mention the enemies could take several precautions or engage in a safer way so in short, it differed greatly from versatile nen abilities like Hisoka's Bungee Gum or Killua's Electricity. 

But, Sachiko liked Carbon Monoxide and especially its name, Silent Killer. It had no odor or color, making it perfect to go undetected. When someone breathed in carbon monoxide, their blood cells would attach themselves with carbon monoxide molecules instead of the normal oxygen molecules, starving the body from the oxygen it needed. The symptoms would go from mild headches, fatigue and nausea and as the exposure increased, the victims could pass out or fall asleep to never wake up again. 

And, the best part about it was people only needed to breathe the gas in for a period of time at a high enough concentration level. In battle, it would be quite easy to focus on fighting and not notice the symptons until it was too late, making it a perfect thing for one of her abilities. 

So, in order to conceal her aura better, Sachiko also started to practice In more even after going back to Hunter x Hunter world. 

She still contacted Satoru from time to time and soon, it had become a routine for them to message a few times throughout the week. Although Sachiko would disappear every other week, Satoru really didn't ask why. And Sachiko really didn't ask Satoru about his overseas missions, although he would often talk about his work with her on the phone. 

All in all, Sachiko loved the new routine she had. 

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

After one month had passed, Sachiko was in Hunter x Hunter world and she had finally managed to transmute her aura into Carbon monoxide with flammable gas properties and named the ability "Silent Death". 

So, for the next step, she practiced In more and she had managed to level up In to Proficient level a week later as she had been practicing for quite a while before.

Since Sachiko's last match was almost two and a half months ago, she decided to register for a match before her match with Hisoka. 

Soon, the date of her match was decided and it turned out to be the next day. 

"Well, I don't really mind." Sachiko muttered as she stretched. "With my current strength, I should be fine against normal nen users." 

Just before her match, she checked her Stats one more time and nodded in satisfaction. Her progress in a little over a month was quite astonishing.

[Cursed technique: Cursed energy manipulation (Proficient), Time Manipulation Eyes (Competent), Nullify (Competent), Pain killer (Proficient), Reverse Cursed Technique (Proficient).

Cursed energy: 50,000/50,000 

Cursed energy reserves rank: B

Nen Techniques: Ten (Proficient), Ren/Ken (Proficient), Zetsu (Proficient), Gyo (Proficient), Ko (Proficient), Ryu (Proficient), In (Proficient), Shu (Proficient), En (Advanced Beginner).

Nen Abilities: Sticky Steel Threads (Conjuration), Silent Death (Transmutation).

Nen Type: Manipulator, Transmuter. 

Aura pool: 112,500 units.

Curse points: 99950.

Hunter points: 220. 

Cursed tools: Special Grade Scythe. 

Skills Intermediate Sword Skill (Competent), Assassins Art: Shroud (Competent), Assassins Art: Silent gaits, Rhythm Echo (Competent), Disguise (Competent).

Abilities: Enhanced sense: Eyesight, Super Hearing, Superior Strength (20x), Enhanced Reflexes, Pain resistance.] 

"Let's go and get the 5th win." Sachiko said to herself, "I wonder who the opponent is.." 

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

"Today, we have a match between Kastro and Sachiko Nakamura! Right now, Kastro has the record of 8-1, just two wins away from the right to challenge a Floor Master!" The commentator announced, "And for Kastro's opponent, we have Sachiko Nakamura, with the record of 4-0. She has never lost a match ever since coming to the 200th floor!" 

"Four wins, straight? That's gotta be pretty impressive, right?" A man in the audience commented. 

Another man next to him replied, "That ain't nothing. Kastro had never lost a match after his first defeat in a match with Hisoka two years ago."

"You mean Kastro got 8 wins straight?!"

"That's what I was saying." 

"If that's true, that girl is in trouble." 

Meanwhile, Sachiko didn't even know she was supposed to fight Kastro. She had always assumed Kastro would fight Hisoka just like in the anime, but as she got to the stage, she realized that the timeline had a lot of changes. 

In the anime, Hisoka had nine wins already after defeating Kastro, when he had a match with Gon but in this timeline, Hisoka had eight wins when he fought Gon. Hisoka and Kastro never had their second match or at least not yet, so Hisoka's win count was understandable.

But, Kastro had eight wins instead of nine when he was matched with Sachiko.

So, it could mean that if Sachiko were to lose, she would be a stepping stone for Kastro to fight Hisoka in the same position as he did in the anime. However, if Sachiko were to win, Sachiko could be like a challenger to Hisoka in Kastro's place.

"Interesting." Sachiko's lips curled up into an amused smile. 

With her new nen abilities, she was more confident. 

A while later, Sachiko was standing on the stage with Kastro. 

"Sachiko Nakamura, is it?" Kastro started, "Sorry but I'll be taking the win today as I plan to challenge Hisoka after getting 9 wins." 

Sachiko chuckled, "That's interesting, for sure. But, I have no plans to get my perfect score ruined." 

Kastro replied, "We'll see about that." 

Sachiko didn't reply, instead, she waited for Kastro to make a move. 

Since she already knew Kastro's nen ability, she wasn't worried at all. She just kept Ken around her body as Kastro charged towards her. 

Once Kastro was in front of her, he disappeared and a fist came from the side. As Sachiko knew this would be Kastro's pattern of attack, she put 90% of her aura into defending the fist from the side while keeping 10% of her aura spread out by using Ryu. 

Of course, it was an extremely risky method since it wasn't much different from using Ko to defend only one part of the body. Once she was hit in the other parts of her body where she was spreading 10% of her total aura to, she would've been severely hurt. 

But, Sachiko was using cursed energy to enhance her body at the same time so even if she got hit in those weaker areas with less nen protection, she wouldn't be injured that much, at least that was what she thought.

With 90% of her aura defending against that one fist, combined with her enhanced body, Kastro's punch didn't deal any damage to her. 

But, Kastro was more surprised at the fact that Sachiko defended the right spot. 

"How?" He asked.

Sachiko smiled, "Maybe I got lucky." 

"You might get lucky once. But, not twice." Kastro said before charging towards her again. 

"You know, luck is a very important skill." Sachiko said, as she watched Kastro getting closer. This time, she predicted Kastro to appear and attack from the other side but as she focused on that area she thought Kastro was going to punch, Kastro kicked her from the back.

Sachiko focused more aura into the area once she realized Kastro kicked there, but the impact made her lose balance a little. Although she turned around and returned a punch immediately after, it only grazed Kastro's robe. 

As Kastro was a master Enhancer, Sachiko felt that there was a significant damage to her lungs from the impact of the kick. If she wasn't using cursed energy to protect herself at the same time, Sachiko would've at least spit out a few mouthfuls of blood. 

Using Reverse Cursed Technique to recover immediately, Sachiko laughed a little, "Apparently, I don't have much of luck. I knew I should've used Ken instead of Ryu." 

"Well, this is fine too." She continued, "I got to figure out your ability a little more." 

Sachiko decided to say the last part so that her knowing Kastro's ability would look like she studied it during the battle. 

Kastro sounded amused at that, "I hope you figure out the rest of my ability before you die." 

"Be my guest." Sachiko said. After the little incident earlier, she realized that while she could use combination of Ryu and cursed energy to defend herself, it was still a little lacking when it came to defending against a master Enhancer. If she were to use Ko or Ken in more balanced manner rather than just defending one spot mainly and combine the use of cursed energy enhancement, it would be a different story but the way she did 90-10 ratio of Ryu wasn't going to work. 

So, she decided to try 80-20 ratio. 

After a few punches and kicks from Kastro, Sachiko miscalculated and found herself being kicked in the shoulder again. This time, there was a sting in her shoulder and she could feel that there was a fracture. 

"Another clean hit! Now, Kastro has scored another 1 point. The score is now 2-0!" The commentator announced. 

Using Reverse Cursed Technique, Sachiko easily healed the fracture, then said to Kastro, "You must be an Enhancer, right? I must say your punches aren't so bad." 

"That's right, I'm a bit impressed at your defense. Most people would be suffering more obvious damage with those two kicks." Kastro replied, "Although it would make sense if you're also an enhancer." 

Sachiko smiled, "I'm not." 

That surprised Kastro. He thought the reason Sachiko didn't suffer any visible damage was because she also had an Enhancer's defense. After all, it didn't make sense for her to not be after being kicked in areas with significantly less  aura in defense. 

Sachiko then continued, pointing at Kastro, "But if you use your Tiger Bite Fist, you might find out what category I am." 

"Very well," Kastro replied, "If you'd prefer to die, then so be it. I'll not be holding back."

Sachiko smiled, "Now, that's where the fun starts!" 

Kastro charged towards her again, this time with his Tiger Bite Fist. 

As Kastro got near Sachiko, Sachiko dodged a little, then when Kastro actually appeared from the other side and attacked her arm, Sachiko used Ko to defend it. 

"How..how did you know I was attacking there?" Kastro asked, his face expression changed a little as he realized it couldn't be a mere coincidence or luck to block his Tiger Bite Fist. And seeing how Sachiko used Ko to defend that only one spot only served to support that theory. 

Sachiko knew where he was going to attack. 

Sachiko smiled playfully, "That's a secret~" 

"Very well, this time, I'll make sure you can't dodge." Kastro said before charging again.

Again, Sachiko used Ko to defend that one spot Kastro was going to attack. 

"How-how did you know it again?" Kastro asked, more panick setting in his face. At the start of the match, he was confident that this would be one of those matches where his opponents knew nothing or could find out nothing about his nen ability even after getting defeated but as time went by, Sachiko kept surprising him with her unusually strong defense and her ability to predict his moves. 

Sachiko noticed Kastro's mental condition and decided to push him a little further, "So, you've found out."

"Found out what?" Kastro asked.

Sachiko looked at Kastro and said one word after another clearly, "That I've figured out your nen ability." 

"That's impossible!" Kastro replied. There was no way Sachiko would find that out in this short amount of time.

"Ara, you don't believe me?" Sachiko feigned an expression of looking hurt, "Your ability is creating double, isn't it?" 

"H-how..."

"Simple," Sachiko said with a laugh, "I've been using my nen ability." 

"Your nen ability?"  Kastro's face fell at that.

"That's right. Although I used a little trick to it." Sachiko replied, still smiling, "If you can't even see it, of course, that means you're hopeless." 

"Impossible...I got stronger after two years...I even got 8 wins straight!" Kastro replied, his voice shaking more and more as he realized he couldn't see through what trick Sachiko had used. 

"You got stronger? Probably." Sachiko nodded before continuing, "But, those wins mean nothing when you're competing with the weak. Do you seriously feel proud after defeating a bunch of broken guys after initiation?"

Sachiko laughed, "Kastro san, you're pathetic." 

As Kastro's face warped in anger, Sachiko felt that it was simply the best feeling to mess with people like this. Although Kastro's reaction was a little too predictable, it was still quite amusing. 

"Shut up. It doesn't matter if you find out about my double. I can still take your life." Kastro said. 

"Then, please try." Sachiko replied cheerfully. 

With anger, Kastro summoned his double and attacked Sachiko together. 

Of course, Sachiko picked the right one out and this time, she sent a kick towards the real Kastro's face. 

"Clean hit! One point to Sachiko!" The judge announced.

"Finally, Sachiko Nakamura has landed a clean hit on Kastro. Now, the score is 2-1!" The commentator announced. 

As Kastro got kicked and knocked back a few feet away, Sachiko added, "Oh, I forgot to tell you. I know how to tell you and your double apart too." 

"H..how.."

"I told you. I used my nen ability. If you still can't see it, you have no hope." Sachiko replied, "You're an Enhancer and your Tiger Bite Fist is quite impressive. It'd be more scary if you actually focused on it and mastered it. But, you decided to waste your potential on creating a body double, which is a conjuration ability. I'm guessing you went through a hell training just to master that and when you finally did, you already forgot how to use nen in other things."

"I..."

"Now, it's my turn." Sachiko said. "Sticky Steel Threads." 

Sachiko conjured more threads and the visible threads were attached to different parts of the stage. 

Kastro looked at the threads and was thinking what move Sachiko was pulling off when he noticed her appearing right in front of him. Her hand appeared to have shot out something but before Kastro could figure out what it was, he felt a sharp pain in his arm.

With a thud, Kastro's severed left arm fell onto the stage.  

"How's it? Are you convinced that you're hopeless?" Sachiko asked.

"You..."

"Or do you want me to take your other arm?" 

"Ahhhhh!" Kastro screamed and started making his double attack. 

But, as Sachiko kept dodging, his face expression fell and soon, he couldn't take the mental strain anymore. His double disappeared and Kastro couldn't defend himself as Sachiko kicked him in the face multiple times. 

It didn't take long for him to lose consciousness and Sachiko won by TK0. 

"Kastro is unable to fight. Sachiko Nakamura wins by TK0." The judge announced. 

Walking away from the stage, Sachiko checked the mission progress and found that there was quite an unexpected development.

[Wins Remaining : 5/10.] 

[Congratulations on winning against Kastro and reaching 50% of the mission progress. Random Reward received. Do you want to open it?] 

'Yeah, obviously.' Sachiko replied.

[Host has received Advanced Hand-to-hand Combat technique.] 

'Hand to hand combat?' Sachiko wasn't really interested in mastering it as she didn't see herself as a close combat type much. But, she decided to still train it from time to time just like her other skills. 

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

Sachiko chan's update stats 

[Name: Nakamura Sachiko 

Alias: None. 

Age: 19 

Relationships: Gon Freecs (Close Friend), Killua Zoldyck (Adopted brother), Kurapika (Friend), Leorio (Friend), Hisoka (Rivals), Illumi (Enemy), Geto Suguru (Enemy), Gojo Satoru (Romantic Interest), Wing (Acquaintance), Zushi (Acquaintance).

Assets 224.7 million yen, 800 million jenny house, 3.75 billion jenny.

Hunter level: B

Jujutsu sorcerer level: Lower Special Grade

Cursed technique: Cursed energy manipulation (Proficient), Time Manipulation Eyes (Competent), Nullify (Competent), Pain killer (Proficient), Reverse Cursed Technique (Proficient).

Cursed energy: 50,000/50,000 

Cursed energy reserves rank: B

Nen Techniques: Ten (Proficient), Ren/Ken (Proficient), Zetsu (Proficient), Gyo (Proficient), Ko (Proficient), Ryu (Proficient), In (Proficient), Shu (Proficient), En (Advanced Beginner).

Nen Abilities: Sticky Steel Threads (Conjuration), Silent Death (Transmutation).

Nen Type: Manipulator, Transmuter. 

Aura pool: 112,500 units.

Curse points: 99950.

Hunter points: 220. 

Cursed tools: Special Grade Scythe. 

Skills : Intermediate Sword Skill (Competent), Assassins Art: Shroud (Competent), Assassins Art: Silent gaits, Rhythm Echo (Competent), Disguise (Competent), Advanced Hand-to-hand combat (Beginner).

Abilities: Enhanced sense: Eyesight, Super Hearing, Superior Strength (20x), Enhanced Reflexes, Pain resistance.] 

----/----

A/N: I know the fight isn't exactly transparent but please read the next chapter where Wing and Hisoka watches and thinks in their perspective about the fight.