BNHA: Spiritual Aura

After Nemuri left, Kai headed to one of the rooms in the house, which had absolutely nothing in it except for its white walls and a strange inscription on the floor. The inscription had a curious appearance, resembling a mix between a circuit and tribal runes.

After discovering that certain breathing techniques could enhance his aura, Kai began searching for more ways to achieve the same effect, which led him to the [Divine Script] and Nen inscriptions. These inscriptions possessed very interesting properties, such as boosting aura or producing curious effects when they detected Nen or making an object incredibly hard and resistant.

Following this line of thought, Kai dug deeper into his memories about these concepts, recalling that although it wasn't explicitly stated, there were abilities that seemed to utilize these concepts to function, like Knov's Hide and Seek teleportation doors. This immediately positioned the idea as something of vital importance in his books.

Determined to recreate something similar, as he couldn't even remember what they looked like, Kai spent years experimenting with the help of Sage and his supercomputer. Eventually, he managed to recreate something that, although he wasn't entirely sure it was the same, worked, and that was all he needed.

However, although this did allow him to enhance his aura, execute certain abilities with a lower cost, and even reduce the difficulty of some techniques. His new [Aura Script], as he decided to call it, couldn't do something that Kai was sure the original could: function as a sort of programming code for Nen.

This idea came to Kai as he recalled the Greed Island arc. The entire concept of the cards, the book, and everything else seemed to function automatically, like the message left by Ging for Gon. It had undoubtedly reinforced the tape recorder where it played so it wouldn't break, while also using Manipulation to control it—all automatically, as if it were a running algorithm. Moreover, if Greed Island was a 'video game,' it had to have something to do with 'programming.'

Because of that, even though it was just his theory, to this day, Kai kept [Sage] using half of his super computer's capacity to search for possible solutions—one of the things that strange ability, or perhaps Hatsu, could do. Since it could control his aura and electronic devices, it could perform experiments at super speed, essentially conducting brute-force research.

"Stay by the door. If anyone comes, don't let them in until I come out."

As he entered the room, Kai instructed Salem, who meowed in understanding before lying down protectively at the entrance. His aura seemed to have not only enhanced the cat's strength and size but also its intelligence.

Once inside the room, Kai sat in the center of the Aura Script circuit in a lotus position, simultaneously infusing his aura into it, always breathing steadily, albeit with a strange rhythm—one he determined over the years to be the best for enhancing his aura.

When the idea became completely clear in his mind, Kai closed his eyes and began to conjure what appeared to be a syringe, which started to materialize in front of him as light. So he quickly called on his trusty assistant.

"Sage."

"Yes, sir?"

"Try to merge with what I'm creating."

"At your command."

With Kai's words, the winged light orb quickly moved toward the syringe, taking shape in the air, causing a light to envelop them. As Kai focused entirely on his aura and the specifications of the ability, he had been developing and testing for a long time.

Initially, Kai wasn't sure how to form pacts, but recalling that Gon only needed his conviction and words for the aura to act on its own and form the pact, he decided to do the same—and it actually worked. So, imagining his aura as a witness, he began to announce aloud:

"This ability will create a parasitic Nen beast that will protect its host in life-or-death situations, even at the cost of its own life. For that, a drop of the host's blood is required to gestate the Nen beast.

The guardian beast will feed on the host's vitality, much like quirks. Under no circumstances can the guardian beast harm the host, and if for any reason the host cannot supply the necessary energy, the guardian beast will enter inactive mode.

The guardian beasts can never attack their host and can only ignore their orders under three conditions: one, by my explicit command; two, if the orders endanger the life of the host; or three, if they contradict an imposed limitation.

The guardian beasts cannot attack another guardian beast or harm the host of that beast. If the host orders an attack, the guardian beast will ignore it, and I will know immediately. Additionally, I will always know if a guardian beast dies or disappears and the causes of the event."

Kai quickly examined the syringe enveloped in light, noticing that it was glowing steadily, which made his expression even more serious. After all, this wasn’t the first time he had tried to develop this ability, but it had always failed, forcing him to try different things and impose new limitations—this was just another attempt.

"The guardian beast will be able to use all my defensive and counterattack abilities and will develop a unique skill that complements its host. To do this, it will need a sample of my blood and all of my aura. After that, even if I recover, I will only be able to use 10% of my total aura capacity until the beast is born in 24 hours."

Seeing the syringe start to flicker, Kai stared at it intently, a bit nervous, as this had always been the step where he failed. He had already tried various approaches, such as giving the host the ability to use aura, utilizing all his abilities, developing a complex Hatsu, and more, but until now, all had failed.

After a while, the syringe stabilized again with a steady light, bringing an immense sense of relief to Kai. Despite wanting to celebrate with all his might, he restrained himself and continued to announce aloud.

"The guardian beast can only use up to 70% of its total aura, but if it dies in combat or the host faces a mortal danger they can't handle, the guardian beast will conjure an impenetrable barrier to keep the host safe."

Seeing the syringe still in place after flickering a bit more, Kai prepared to give the final instruction, a crucial one that could potentially cause the entire process to fail.

"The guardian beast can be updated with my new strength and abilities, but to do so, I will need to give it a drop of my blood and all my aura. The process will take 24 hours, during which, even if I recover, I will only be able to use 10% of my total aura capacity."

With the final instruction, the syringe began to glow intensely until, at last, the light faded, leaving behind a beautiful antique-style syringe that appeared to be entirely made of metal. With engravings all over its surface resembling the pattern of the Aura Script on the floor.

"IT WORKED!!!"

Seeing the syringe, Kai jumped up in excitement, shouting with all his might, which immediately alerted Salem, who hurriedly got up from the floor, only to meow in annoyance as if complaining about the scare.

"Hahaha, finally, I almost didn't make it!"

Paying no attention to the annoyed Salem, Kai took the syringe in his hands, grinning from ear to ear, and then studied it closely, utterly fascinated by his success. But soon after, the syringe in his hand began to change shape and glow, turning into a ball of light with wings.

"Sage, what happened with the ability?"

Seeing his reliable assistant again, Kai immediately asked, full of curiosity, soon receiving the answer he expected.

"The ability has been successfully integrated into my functions. I can now monitor the guardian beasts at all times and, through them, monitor the physical state of the hosts."

"Perfect! Just what I was hoping for, hahaha."

Completely satisfied, Kai took the ball of light in his hands and kissed it, to which the light orb did not react and simply continued to float steadily after being released, as if it was used to this.

"Well, now I just have to wait for Onee-chan to arrive to create her guardian beast, although I need to reinforce the security system since I'll only have my Haki for 24 hours..."

While thinking about how to organize the creation of the guardian beasts, Sage disappeared, as it wasn't needed anymore and still had experiments to run. Meanwhile, Kai left the room, closely followed by Salem, who walked beside him with a steady, calm stride, like a faithful follower.

"For now, Nejire and Aunt Yumiko are on hold until they return to the country. Onee-chan will be today, and for the Pussycats, it's best to ask them to take a day off every three days to create their guardian beasts. As for Momo and Aunt Keiko, if I'm not mistaken, they arrive tomorrow, so they'll be next, although I suppose it's better for Aunt Keiko to have her guardian beast first..."

As he organized a schedule to grant the guardian beasts to his family, Kai made his way to the living room, where he sat on one of the sofas and took his computer. He began reviewing the entire security system, while Salem lay down on one of the nearby sofas.

After checking the entire security system, Kai reviewed the information on the guards who were stationed at the entrance to the property. These guards were retired heroes that Nemuri had hired several years ago, and since they worked in shifts, it was best to double-check those who would be on duty during his time of vulnerability. After all, it was better to be safe than sorry, especially with his lousy luck.