Deep into the forest, concealed by the waterfall that flew over its entrance, lie a hideout, built onto the side of the mountain.
After surveying the surroundings, Kakuzu slowly approached the facility. Detecting no shinobi outside, he made his way inside.
The hideout was eerily quiet. Kakuzu navigated the labyrinthine corridors. Easily avoiding and disarming the concealed traps that were left behind.
After delving deeper into the building for some time, he detected chakra signatures moving towards him. And sure enough, he heard the sound of footsteps nearby.
• • •
The three guards tasked with the patrolling duty were in a troublesome predicament.
After Orochimaru's disappearance, most personnel left the place. And like others, they too planned to leave. Unfortunately, however, before they managed that, they caught eyes of a crazy scientist who decided to keep them around. And because of that, they were stuck in much worse situation then they were before.
„What the hell are we guarding here? This is crap!"
Dissatisfied with the state of things, one of the guard, although rather pointlessly, complained.
"Stop asking stupid questions, Nakaji."
"I'm serious, Hoji. The snake bastard's dead. Without him, those leftover idiots aren't going to last long either. Sooner rather than later, they're going to get hunted down, and we'll be first to go down."
"You know damn well why we we're stuck here. You're telling me you need another reminder, huh?"
"Yeah, yeah… we need that antidote, got that. It still pisses me off."
"Just keep this in that empty head of yours - We'll die without it. For now, only thing we can do is to keep obediently working for the old man."
„You're calling that guy an old man? What is he, your grandpa? Ha, Hoji? That bastard's is batshit crazy. I'm telling you man, even Orochimaru wasn't that cruel. Who in their right mind treats their guards like this? How long is it gonna take until we are discarded like others?!"
"You think we're happy, genius? It's just unlike you we know when to keep our mouths shut."
"Ugh… yeah, I get that. All I'm saying is - Let's just ransack this place already and bounce. We can make some medical ninja to cure us. Wouldn't that be better than sitting here like rats? Cause that's what we are. Rats sitting in the box. "
Listening two bickering with each other, third one decided to chime in:
"No guys. We're not doing that. Not yet at least. If we're going to try anything, we better come up with a damn good of a plan. Old man's weak, but he's not dumb. If you thought that far, he has too."
"Haa... I get that, alright? Just come up with something already, I'm getting impatient."
„Rather than telling him what to do, just keep your mouth shut. If are going to mess up again, he's gonna kill us himself, before poison does."
Nakaji's face twisted in annoyance as he thought about his predicament.
„... Tch, I don't plan to die uselessly like that."
Then suddenly, they felt intense pressure boring down on them. They froze, unable to take another step.
Air whistled, as if something shot forward with a high speed.
Next moment, they were swiftly encased with some kind of black rope and were knocked unconscious.
• • •
Getting rid of the guards wasn't hard. Which wasn't surprising, considering that their chakra didn't seem to exceed that of an average chunin.
Then, what was he going to do to those thugs? They were useless to him. Interogating them was risky. As it might alert others of his presence.
Kakuzu approached one of the guards.
There were things about his abilities he was curious about. And coincidentally, those things required human sacrifice in order to figure out.
Then, why not use this chance run an experiment?
He arranged threads in front of the guard's chest, where the heart would be. Part of them covered up the mouth, making sure no sound would escape in case guard woke up.
Before moving the threads, however, he hesitated.
He felt uncomfortable about his lack of response. Maybe it wasn't about killing itself that bothered him. But the fact that he felt almost nothing about taking another person's life. Maybe it was about him being only just a little reluctant in doing so.
Kakuzu's memories that were full of cruelty of shinobi life made him desensitized to the killing. As a result, it seemed that his moral values were a bit screwed.
"... Ah whatever."
He shook of those thoughts. He was certain that this wasn't going to be last time he would be doing something immoral. It was better get used to it sooner then later.
And then, threads pierced the heart of the guard and Kakuzu let his chakra flow into it.
Question rose in his mind: What would happen if he tried to absorb sixth heart?
Although Jiango could allow user to stock up the hearts, number was limited to five.
So, what if he tried to exceed the limit?
Truth was, Kakuzu already knew the answer to that question. Implanting an extra heart modified user's chakra system. However, by adding sixth heart, the body wouldn't be able handle that much of a strain. Well, that's what his memories were telling him. But Kakuzu had a hunch that some things might be different than his experiences.
As he was done with extraction process, he started drawing the heart inside his chest. Proceeding in a way that Kakuzu would normally take to restore the lost heart. Instead of immediately absorbing it, however, he chose to take a safer approach.
A scar on his chest opened up and threads came out from it. Threads, already connected to the heart were cut of and reconnected to the ones coming out of the chest. Then he started drawing srill beating heart inside his chest.
When he did so, something interesting begun occurring. His body started overfilling with the chakra. And soon, it started rejecting any further intake of energy. Sure enough, he stopped at that; continuing process would be akin to a suicide. Kakuzu wouldn't truly die, per say, but extra heart was causing instability in his body and chakra system. And as if to compensate this, one of his hearts had started beating faster. Slowly, gradually enlarging with each beat. As it seemed, it would explode from the chakra overload. Leaving place for the new one to be implanted.
Kakuzu obviously didn't let that happen. He would be replacing stronger heart with the weaker one if he did so.
He dropped the body. The heart was unusable after the process failed. It turned into a goo of blood after he retrieved the threads. He then approached next guard and started doing the same thing again.
He infused the chakra, pierced the heart with his threads.
But this time he tried a different aproach. Instead of drawing heart towards him and establishing a connection, he let the chakra build up and stay inside the guard's body. He wasn't sure of result. However, he still did this, purely to satisfy his curiosity.
Interesting thing Kakuzu noticed was, that he seemed to somewhat be able to sense the level of the heart after connecting his chakra to it.
"Hmm... His chakra intensity is around same level as the previous one. But still, there's a difference… It' like… Oh… I've got an idea. How about I assign a certain rank to the each of the individual heart? "
Well, he did like the idea. It would simplify thing and would allow him to keep track of their potential.
Then, by following those thoughts, level of heart of an average chunin would have around rank F. Average jonin - around E. And so on. Kakuzu was going by apsects such as vitality and the talent in chakra affinity. This particular ninja for example, had around G- rank heart. In short, he was little better than hot garbage in his standards.
Although, those rankings were purely speculative, and based on Kakuzu's experiences. Still, they should be fairly relevant to serve it's purpose.
Chakra started to spreading throughout guards' body and after few minutes, something begun to change. Whole body, and not just the heart, starting from skin, to the muscle and then even to the bones started turning into tendrils similar to his. First, they were torn to shreds, and then, they begun to transform into black tentacles. It took about dozen minutes, but when the process was almost complete, tendrils started to form a blob of swirling mass which kept intervening with each other.
Kakuzu grinned. The experiment was success. He took that as a cue that jutsu was in it's final phase and took out the storage scroll.
Sealed inside the scroll was something he personally prepared beforehand. Though he wasn't expecting to use it for this occasion, or at all anytime soon. After all, it was just a failure he made during his free time.
What he summoned from the scroll was a mask, adorned with same patterns as Kakuzu's fire affinity heart. And it was a necessary part of the justu.
In order to finish the Eart Grudge Fear, caster needed a mask designed for an specific affinity the heart possessed. In the back side, the mask had a seal placed that bind the heart to it. And while making them wasn't that much of an challenge, Material and the seal used determined the quality of the mask.
Mask had to be durable enough for it to be able to contain the chakra of the heart. Otherwise, the heart, as well as mask would go to waste. One should also be aware that if the mask was destroyed, the spirit - or whatever that creature was called - would also die. Same went for the Seal.
Kakuzu gave making the mask a try while waiting for his minions to return. And as for the result – Well… it wasn't bad considering it was his first try.
He made few more of them with varying quality. In the end, neither one was of the level of the ones atached to his back. And while needed more practice to get used to the craft, he was improving rapidly. Which wasn't much surprise since he had all the knowledge needed while his body had muscle memory already ingrained into it..
Kakuzu also had a dozen of masks saved up from the few years prior. They were ones made by original Kakuzu, which, unlike the ones he recently made, had much finer quality. They were prepared just in case he needed a new life point.
Kakuzu didn't plan to use one of those for now however, it would be a waste for this particular heart.
He took the mask and placed it on the blob of threads. When the chakra infused threads touched the seal on the mask, it caused it's activation and it slowly started binding with the heart. Outer part of the mask was pierced by the threads and spirit started to take a form. Mass of threads grew arms, legs and tail. It was default appearance determined by the seal. Looking similar as to what his fire affinity heart looked.
„Fascinating, hmm… I wonder though. If I modified and tweaked the seal a little, could I make something resembling to the dragon? With possessing the ability to breath fire, flight and massive vessel, it would trully look like a magnificent, mythical beast-" Kakuzu shook his head. "No, wait. What am I thinking."
He wasn't sure why he suddently started to daydream. Maybe stress was finnaly getting him. Or finding something interesting after hours of an uneventful journey made his thoughts trail off momentarily. The thing was, he should move on until he was discovered. Experimenting with stuff and creating something resembling a mythological creature seemed exiting thing to do, but that could wait for later.
After fire spirit took the form, it stood there without moving. It just stared at it's creator.
„Alright... I don't remember Kakuzu being able to do that. But it's similar to the ones I already have in my body."
Did him replacing him affect this body somehow? That wouldn't be too farfetched of a theory but it was still concerning possibiliy.
As for the spirit standing in front of him, he could feel a thin connection form between them.
After observing for a while, Kakuzu tried something. With a mental command, he ordered the spirit to take a few steps left. Immediatey, it did just that. Then it obeyed it's next intruction, picking up the body of remaining guard and bringing it to him.
It seemed the spirit didn't have ability to form the complex thoughts. It couldn't talk, nor did it act without orders. In short it was a puppet.
He repeated the process with last ninja. Few minutes later another fire spirit stood before him. It was identical to first one, albeit a bit weaker. Kakuzu was pleased with the development. Having puppets to his arsenal would be an useful tool.
That said, currently the ones before him were weak. Disappointingly so. They would struggle to win even against average chunin. However, that was no reason to complain. If this ability allowed him to create stronger puppets, he would have perfect army under his disposal.
Kakuzu left the masks in the hall and ordered them to notify if someone approached. He, on the other hand, continued moving deeper into the hideout. Since there were guards, then there was high chance that someone important was here as well. He continued advancing further.
After some time passed while was searching the place, Kakuzu heard an yelling from somewhere lose by. The sound echoed through the air as it caught his attention.