BNHA: Spiritual Aura

After arriving at the yacht, Ryuko and Shino took Kai to one of the rooms, where the blue-eyed boy fell asleep the moment he touched the bed. This brought affectionate smiles to the faces of the pair of beautiful women, who looked at each other somewhat amused.

"It seems he really gave it his all, fufufu." Shino commented playfully in a low voice, to which Ryuko nodded equally cheerfully.

"Yes, he looks so cute all tuckered out, but let's let him rest. Let's join the others."

After a couple more giggles, the pair of beautiful women left the room to meet up with the others on deck. Meanwhile, a black cat with blue eyes discreetly slipped into Kai's room and settled next to his master on the bed.

...

The next day, Kai opened his eyes with the first rays of the sun. He sat up in bed while stretching, and after a moment, he got up and headed to the bathroom, wanting to take a good shower while summoning his reliable assistant.

"Sage."

"Yes, Master." As she materialized, the beautiful fairy spoke with a small smile on her face, to which Kai asked a bit more seriously.

"Were you able to obtain all the data on my performance and All Might's?"

"Yes, Master. From his combat method to how his special cells worked, which helped clarify several doubts about his strange quirk." Sage replied in a serious tone while showing Kai a holographic screen summarizing the data.

"One for All really doesn't seem like a quirk at all..."

While reviewing the information, Kai couldn't help but vocalize the thought that had been circling in his head since he first analyzed One for All. After all, that quirk was too strange; more than a quirk, it seemed like a super-sophisticated DNA editing 'device'.

The curious conclusion Kai reached about One for All was due to how it worked. Based on the tests and data Sage had obtained, Kai determined that this 'quirk' functioned almost algorithmically, following a set of structured steps that seemed to have a specific objective, especially since there were a couple of extra 'unnecessary' steps.

The way One for All worked was that upon entering a new body, it mutated by referencing the unique characteristics of the new DNA, strengthening itself in the process. At the same time, it modified the new host's DNA to adapt to its existence. In return, it allowed the use of different abilities, such as 'accumulation', which did not function like any normal accumulation quirk and was possibly the result of several mutations.

The accumulation of One for All worked by turning the host's entire body into a kind of energy generator. It modified all the body's cells to exponentially increase their production of what he decided to call 'bioenergy', which was the power source of quirks.

That was why, despite supposedly being 'accumulation', All Might never ran out of energy. It wasn't because there was so much energy that it never depleted; it was because he wasn't accumulating energy in himself. What One for All did was progressively modify the body's cells to increase their capacity and maximum production of 'bioenergy', which resulted in All Might's brutal set of abilities.

But as if that weren't enough, One for All had the ability to modify itself to integrate the abilities of other quirks into itself, creating perfect copies of those abilities that integrated seamlessly into its structure. However, according to a small experiment by Sage, this meant that a person with a quirk would suffer great physical stress due to this, which could bring serious health problems. 

But that's where the strange extra 'unnecessary' steps of the One for All came in. Although he still lacked data to confirm his theory, Kai knew from the little he saw of the series that when All Might passed on his quirk, he began to lose his abilities quickly, which didn't make sense—after all, the modifications were already made. 

Furthermore, even though all the genetic information was there along with the necessary quirk factor, All Might couldn't use the additional 'abilities' in One for All aside from 'accumulation', which was quite strange, to say the least.

This led Kai to consider a possibility: One for All didn't abandon the previous host but actually duplicated itself in the new host's body. Then, it began to reverse the changes to take away the abilities, giving the false appearance that the quirk had 'abandoned' the previous host. The question was, why did it do this? From how it worked, there was no real need to do so.

This led him to realize two things. First, there was a vital part of how One for All functioned that he didn't know, or even about quirks themselves. Second, and more importantly, that quirk was too strange and gave him an evil feeling, so it was better to dismiss any idea he might have about having it. Although, well, he never wanted it in the first place, so that part was easy.

"Well, with this, we have what we need to start our little research project to replicate the 'accumulation' of One for All to enhance the girls' quirks and maybe mine." After turning off the shower, Kai commented while drying himself, to which Sage responded with a serious expression while displaying a different holographic screen.

"Understood, Master. I'll begin exploring the possibilities of using aura to reproduce a similar effect, using invasive medical means, and developing external devices."

"That's fine, but focus mainly on using aura. Using external means might work for the girls, but not for me." As he left the bathroom, Kai ordered in a serious tone, to which Sage quickly nodded.

"Understood, Master."

"Also, run several simulations of the battle with All Might, but with me going all out."

Kai added in a serious tone, since, although it was likely that All Might hadn't shown all his power either, he wanted to see how his other abilities would have worked. He preferred not to show up unless absolutely necessary. After all, they would be his trump cards, and he had already made a strong impression; any more than that could cause serious problems.

"Understood, Master. I'll run a complete simulation and even adjust All Might's parameters to use all his power according to the estimates we can make with the current information." Sage nodded seriously while her wings glowed in various colors, to which Kai nodded, truly satisfied.

"Perfect."

After changing clothes and ending up in simple black shorts and a white hoodie, Kai headed to the yacht's main living area. The main living area was decorated in a minimalist and modern style, with comfortable sofas and a huge screen at the front, where Ryuko was playing an adventure video game.

"Good morning."

In a casual tone, Kai greeted the beautiful woman on the main sofa, who was dressed in a simple white summer dress that seemed to highlight her almost divine beauty. She turned to look at him while patting the spot next to her with a smile.

"Good morning, Kai. Let's play a bit."

"Sure."

Comfortably, Kai took a second controller from a nearby cabinet, then sat next to Ryuko, who smiled cheerfully before switching the game to a fighting one, speaking in a challenging tone.

"Hehehe, today you're going down."

"We'll see about that," Kai responded with a slight smile, then chose a character and started the battle, easily defeating Ryuko, who quickly retorted with an annoyed look.

"Hmph, I was just warming up. Next time, I'll play seriously."

"Hehehe, let's see then."

After several consecutive defeats, Ryuko let the controller drop onto the sofa with exasperation, then lay down with a pout, resting her head on Kai's lap, though she turned her head away so as not to look at him.

"You're so annoying..."

"Hehehe."

At Ryuko's comment full of frustration, Kai could only smile amused while stroking her silky golden hair, which greatly relaxed the beautiful heroine. After a moment, she asked in a low voice.

"Did you enjoy the duel with All Might?"

"Quite a bit. It was a good experience, although I'm still far from what he can achieve. Eventually, I'll surpass him; it's just a matter of time." Kai responded casually without stopping his stroking of Ryuko's hair, who, after remaining silent for a moment, couldn't help but ask with a tone full of mixed feelings.

"... Kai, would you really not consider becoming a hero?"

"The truth is, no. That profession doesn't hold any appeal for me. I like being anonymous as much as possible, and besides, I'm quite rich." Kai once again expressed his answer to the question that everyone in his family had asked him at least once.

"But with your abilities, you could save so many people..." Ryuko commented in a disappointed tone, as, although she had heard the same answer several times, it still seemed a shame to her.

"Well, maybe so, but why bother? After all, I'm an unstable person with severe mental problems; why would anyone ever need my help?" Kai responded with a scornful tone, which brought a look full of pain to Ryuko's face.

To this day, if there was something in their family that she considered the greatest tragedy that could have happened to them, aside from the death of Kai's parents. It was undoubtedly the media circus that was made around Kai's 'mental stability'. Something that, no matter how much they tried to silence, was not possible—although many 'celebrities' ended up either in jail or without a career in the process.

Whether he used it as an excuse or if it had really impacted him, Kai always ended conversations about being a hero with that phrase. It was almost as if he were expressing that his father's years as a hero had been for nothing. In the end, all he gained was a tragic death and he, as his only son, the stigma of being crazy.

"Kai, you know that doesn't represent the majority... It's just a minority who were swayed by what the press said, and many of your father's fans defended you tooth and nail. Besides, a lot of time has passed..." After a moment, Ryuko explained in a low voice, to which Kai only smiled while stroking her golden hair.

Kai's silence could only bring a sigh from the beautiful heroine, who closed her eyes while different feelings fluctuated in her heart. In her eyes, Kai was the perfect man; he had everything she had always dreamed of in a husband: he was handsome, rich, capable, strong, and, above all, protective and home-loving. But there was a small flaw, one that she couldn't help but feel a little itch about: his indifference toward strangers.

But at the same time, she understood that for Kai, being a Hero was a somewhat delicate subject, since it wasn't just his indifference toward strangers; there were also unresolved feelings that Kai refused to let go of, to the point that, even though he had never mentioned it, not even once, they, who had been his family for many years, could easily notice it.

"...But you know, although I won't be a hero, you already are, and just as you strengthened yourselves with the help of the Accomplices, over time I'll create new things to empower you. So, in the end, the people I don't save, you'll end up saving, and who knows, maybe you could even become the next symbol of peace or something like that."

After a moment of silence, Kai commented with a smile while stroking Ryuko's hair, who couldn't help but turn her head to look directly into his eyes. After a moment, she threw herself and hugged him without saying a word.

With a somewhat amused smile on his face, Kai began to gently stroke Ryuko's slender back, who hugged him tightly. After a moment, she whispered in a voice full of feelings.

"You're really the best, Kai."

"Hahaha, not at all. I just want you all to be happy, and being heroes makes you happy; I'm more than willing to help." Kai commented warmly while returning Ryuko's hug, who seemed to melt in his arms, then commented in an almost dreamy voice.

"Kai... let's get married when you turn 18."

Kai couldn't help but open his eyes in surprise at Ryuko's typical confession, which was now loaded with feelings and reflected the seriousness with which she said it, putting him in a real bind. After all, he had promised not to mention his relationship with Nemuri, which left him with few options to reject the proposal of such a charming woman.

"... The future is uncertain, and many things can happen; it's better we live calmly and see what life has in store for us."

Not being very sure what to say, Kai tried to take the diplomatic route, but to his surprise, Ryuko freed herself from his embrace to look him straight in the eyes for several seconds, which seemed like hours. She then gently placed her forehead against his while closing her eyes, and she commented with a tone full of determination.

"I'm serious. I want you to be my husband and the father of my children. So from now on, I'll try to win you over with all my might and make you fall at my feet so we can have a lovely wedding when you're older, so get ready, hehehe."

After saying what she needed to say, Ryuko laughed mischievously, which somehow made her look like a naughty cat, then jumped off the sofa and ran cheerfully out of the room, leaving Kai with his eyes completely wide open.

"Sage." After a moment, Kai called Sage, who immediately appeared at his side. With a serious tone, he ordered.

"Read Ryuko's feelings."

"Immediately, Master."

Along with her response, Sage quickly used the AP Field to determine Ryuko's feelings, since although Kai could vaguely sense feelings with his Observation Haki, they were very diffuse to him, almost as if they were musical notes. While he could differentiate two very different notes, he couldn't name them, even if his life depended on it.

"Master, they are love, joy, embarrassment, and hope." After a few moments, Sage responded while looking at her master, who couldn't help but open his eyes in surprise.

"What...? Are you sure, Sage? No negative feelings? Anger, anxiety, rejection? None of that?"

"No, Master. In general, Ryuko is in a very good mood." Sage shook her head while responding, which only worsened Kai's confusion. He couldn't help but comment, stupefied:

"I really don't understand women... although I think I should talk about this with Onee-chan..."