(Pov Satoshi)
Once he said those words, the environment rapidly changed around me. The old factory suddenly came to life with conveyor belts running, and I could hear a slight hammering noise in the distance. Suddenly, this situation had gotten much more difficult. I had been confident before about killing this guy quickly, but now that we were both in his domain, that wouldn't be so easy. Still, I had one more ace up my sleeve, at least I hope I had it, never got the chance to put this to the test.
He lowered his hands, his previously furious look replaced by a much more smug expression. "Well, what do you think? I have reached the mastery of Jujutsu, and I know the other one doesn't have his own domain, so any last words, I'll be sure to let your precious brother know before I kill him too." He said already preparing to use his technique.
I said nothing and charged at him right away. His technique worked best at range, so the closer I could get, the better the downside was. He knew this too, and leaped back before I could strike, activating his technique as he did so. Above me materialized a large industrial hammer typically used for pressing metal into large sheets. I was somewhat surprised to be able to see it instead of the usual haze from techniques, though this was most likely due to being inside his domain.
I rolled away, causing the hammer to smash into the ground where I had been, which confirmed I was right; I did have that ace, and he had no idea. "How did you do that? This is my domain, you don't know any anti-domain techniques, so tell me how you dodge my technique?!" He was losing it; his supposed trump card had failed him, though he couldn't possibly have known why his domain wasn't activating its sure hit effect. I hadn't even been sure this would work, but it had, and that's what mattered.
"Oh, you want to know how? Did you really not notice my lack of cursed energy? Your domain can't differentiate me from any other non-living object your sure hit won't work!" I yelled back at him something I had known, but never had the chance or desire to test in case I had been wrong. It was one of the other side benefits of having such a restriction, as it meant that barriers and even domains didn't consider me a person but instead as a thing, so I could traverse them freely. As such, I could dodge attacks inside a domain like I was still outside it, though I would have to watch for whatever other effects the domain might have.
'I can't let him get the upper hand back. I'll need to knock him down hard enough that he loses his domain, then he'll have no chance.' I thought knowing if I delayed, he might come up with some other trick, not to mention even if they lacked the sure hit, the power behind them would certainly be boosted, and he might get lucky. I launched myself off the ground towards him, pulling my fist before smashing forwards slamming into his gut, knocking him back. I pressed my attack using the hands till holding my sword to make another swing, and this time my blade finds the target. The blade passes across his chest, leaving a massive gash across his torso.
With the damage from this attack, I had assumed it would break his domain, but surprisingly, the structure still held. I looked over to Taro and noticed something that would make this fight much harder: the wound on his chest was closing. He must have developed Reverse Cursed Energy at some point.
Cursed energy came from negative emotions, and this allowed for it to cause damage; as such, it could be used in a technique or to reinforce your body to attack and defend. The issue, though, was that it couldn't restore due to the negative nature of it, but if you were skilled enough, you could multiply the cursed energy against itself. Multiply a negative by another negative, and you get a positive, so by mixing the negative cursed energy with more of it, you could create Reverse Curse Energy, which could be used to heal wounds and, if it was strong enough, even restore entire limbs.
'This guy was made to be annoying, wasn't he?' I couldn't help but think that what I had thought would be a regular, somewhat easy battle had now turned into a much more drawn-out process, and it made no sense. This guy wasn't some genius or anything; his Grade came from the destructive power of his technique, and that was his limit. So, how had he learned not only domain expansion but also how to use RCE? I'd have to ask him after I finish beating him first.
I charged once again, only to find myself barely able to stand as the ground began to move. I looked down to notice the entire floor had become a series of moving conveyor belts, another aspect of his domain, most likely. He looked worried, at least so I had to be wearing him down by now, but finding my footing was proving difficult. Finally, I saw an opening as the belt I was standing on ran under a catwalk, allowing me to climb above the shifting ground, though he wasn't letting me go that easily. As soon as I made it up, another hammer came crashing down, just barely missing me as I rolled away.
I began to run down the catwalk as more hammers smashed down behind me. Finally, I saw my chance with my free hand, I drew Slaughter Demon from its sheath and threw it at Taro. The knife wasn't made to be thrown, especially with such a wide blade, but put enough force behind it, and anything becomes a throwing weapon. The knife sank into his shoulder, causing him to yell out and, most importantly, lose concentration.
The domain barrier shattered, and the old factory returned to normal apart from the damage dealt by the falling hammers. I put my sword back in its sheath and approached the fallen curse user as he struggled to stand. A domain was the most energy intensive actions a sorcerer could take, and once it was over, their energy was usually mostly gone. Not to mention, he had been running the RCE to heal himself from my attacks. Once I got closer, I grabbed his collar and lifted him to have a quick chat.
"How did you develop so quickly?" I asked
"Why should I tell you anything?" He spat. He was sweating now, and he was scared.
"Because I will kill you quickly if you tell me." I had considered lying and saying I'd let him live, but he would know he had signed his own death sentence with his actions, so the best he could hope for was a faster death.
He weighed my words for a moment before he sighed and spoke again. "I was approached by a woman who helped me unlock my potential in exchange for trying to kill the child from the Gojo clan with white hair and blue eyes."
I hadn't expected him to say that, but a cold feeling of dread settled in my stomach. "What did she look like? What was her name?" I asked, though I somehow knew what he would say next.
"She never told me her name, but she had dark hair, oh, and this weird line across her head." He said, shocking me enough that I almost dropped him. This was bad, really, really bad. I knew who he had met, and if he was getting involved, I was in big trouble. The "woman" he had met was, in actuality, an ancient sorcerer with the ability to swap himself into new bodies and had been doing so for a thousand years.
Kenjaku the reason for so much of the bad that happens in this world. He was the one who helped split Sukuna into his fingers. He was the one who took over the body of Kamo Noritoshi and created the death womb paintings. He wanted to merge all of Japan with Tengen to create a new world of Jujutsu, and his plans were put in motion when Toji killed the Star Plasma Vessel. I had been so caught up in getting stronger, I had forgotten what time it was and what was going to happen, maybe already was, and Kenjaku knew somehow he knew I would be sent on this mission; this whole thing was a distraction.
I gave Taro one last look before breaking his neck and retrieving Slaughter Demon. I had to get back to school as soon as possible; if I couldn't, then nothing would change, and the world would begin its downward spiral.