"Sir, Nohara Rin has accepted your invitation, but she wants to speak with you personally."
Hyuga Mirai, who had been analyzing the application of Sage Chakra, suddenly received a message from Number 18.
"She made up her mind this quickly?" Hyuga Mirai checked the time—it had only been a little over ten days. He had originally thought that Rin's feelings for Konoha would take months to fade, that she would have to be pushed to the edge before deciding.
"Then transfer the image, Number 18."
A moment later, the video feed revealed Nohara Rin's face. Her complexion looked healthy, and she didn't seem mentally drained from being in a tough spot.
"Mirai-kun, is everything you said true? Ten years... and your goal?" Rin asked.
"Of course, I have no reason to lie to you. In fact, aside from the Three-Tails you can call upon at any time, there is nothing else about you that concerns me. And in every aspect, Ayaka Uzumaki is far more capable than you. If you have any questions, you can always ask her," Hyuga Mirai said, glancing over at Ayaka. Hearing this, Ayaka proudly puffed her chest, standing taller than Rin.
"I meant medical ninjutsu and chakra," Hyuga Mirai quickly added, putting Ayaka's pride back in check.
Rin sighed lightly before speaking seriously, "Then, I accept your offer, Mirai-kun. I hope you won't deceive me."
"Trust me, you won't regret it," Hyuga Mirai assured her with a smile. After that, he turned to Ayaka and said, "Ayaka, handle the sealing on her, using the Four Symbols Seal as a base. Allow one-third of the Tailed Beast Chakra to leak, and add a Five Elements Seal for further protection."
When dealing with Rin, he couldn't trust her as much as he did Ayaka, but Rin's medical ninjutsu and ability to seal the Three-Tails would be useful. If the Tailed Beast Chakra exceeded the allowed limit, the Five Elements Seal would trigger, working in conjunction with the Four Symbols Seal to prevent Rin from using any chakra at all.
There was also another layer of protection he needed to add: the miniature explosive device embedded in her, connected directly to her flesh. This bomb could destroy everything within a fifty-meter radius and would activate quickly. No one in the ninja world could disarm it.
"Understood, leave it to me, Mirai-sama!" Ayaka said confidently, her chest out as she spoke. Having become skilled with the she could now quickly subdue the Three-Tails if it ever went out of control in Rin's body. The Adamantine Seal was especially effective against Tailed Beasts; even the mighty Nine-Tails would find it difficult to resist a fully empowered Uzumaki user wielding this technique.
After assigning Rin's task, Hyuga Mirai ended the video call, much to Ayaka's reluctance.
He then lay back on his bed, connected to the surveillance data, and continued his research on the feasibility of Sage Chakra's permanent enhancement of bodily organs.
Ordinary summoning beasts that absorb natural energy can greatly extend their lifespans. Creatures like the toads and snakes, who would typically live for only a few decades, could live many times longer after absorbing natural energy—unless something unexpected happened.
"Though the speed has slowed a bit, the natural energy still dissipates. There's no reference sample for the main body, so it's difficult to proceed." The shadow clone, after researching, spoke up. Without sealing techniques, keeping Sage Chakra in the body long-term was very difficult. But with sealing techniques, the Sage Chakra would not have an effect on Hyuga Mirai's body.
Natural energy and chakra are essentially different; any foreign energy that invades the body will trigger its natural rejection. Sage Mode allows for the control of natural energy, balancing all three energies within the body. If the balance tips even slightly, it could cause a backlash from one of the forces.
"I understand. I'll get a sample," Hyuga Mirai said, deciding to call for one of the Snake Sisters. Since White Snake Sage had shown favor, it would be a waste not to use it.
"Summoning Jutsu!"
Hyuga Mirai formed the hand seals and released a large amount of chakra. The Three Snake Sisters from Ryūchi Cave could have been summoned earlier through a summoning contract. But after they reached a higher level of Sage, they had removed the seals on the summoning scroll. Only when White Snake Sage spoke to him last time did they leave Sage Chakra with him, allowing him to summon them at any time.
A puff of smoke filled the room, and from within, a figure floated out—a young girl with blue hair, a simple crown, and wearing a white long robe.
"Can you also change into human form outside? I would have summoned you sooner if I knew," Hyuga Mirai remarked to the girl, who resembled a little loli. This was the Snake Sister, Ichikishima-hime, one of the Three Great Snake Sisters.
"Maintaining a human form is due to the sage chakra, not the environment of Ryūchi Cave."
Ichikishima-hime looked around, but seeing there were no enemies, her energy seemed to drain, and she hung her head in disappointment.
"So there's no enemy? I thought I'd get a good meal."
"Looks like no enemies have disappointed you. I summoned you this time to ask for a favor. Please come with me."
Hyuga Mirai walked towards the underground base. Since Ichikishima-hime could maintain a human form, he wouldn't have to bring his experimental equipment to the surface.
"Do you enjoy eating humans? Next time I summon you, I'll prepare extra food for you."
"It doesn't have to be humans. Any chakra life form on the brink of death is fine. Frogs would be even better. Humans have plenty of chakra, but the frogs from Mount Myoboku suit my taste more."
Ichikishima-hime floated beside Hyuga Mirai, speaking in a light and airy voice.
"I see. You must have heard from Kohaku about it eating frogs from Mount Myoboku. There's no need to stay so close. Next time, I'll summon you."
Hyuga Mirai reached out, preparing to push Ichikishima-hime away from his neck, but his hand passed right through her face, unable to touch anything. At the same time, Ichikishima-hime's figure appeared ahead of Hyuga Mirai.
"Is this an illusion?"
Hyuga Mirai suddenly became interested. The ability to deceive his senses was rare. Although he hadn't activated his Byakugan, not many illusions could fool him.
"Sage Mode!"
"Byakugan!"
Hyuga Mirai immediately activated both abilities, but the Byakugan only revealed a mist-like chakra, and he couldn't see Ichikishima-hime's true form. However, in Sage Mode, he could barely sense where she was located.
"That's barely an illusion. It's a snake's instinct. By secreting fluids from its skin and mixing it with sage chakra, it creates a hallucinatory effect. Even dojutsu can't see through it. Only those who have trained in Sage Mode can vaguely sense my presence."
As Ichikishima-hime spoke, she retracted the surrounding sage chakra and, with a hint of surprise on her face, said to Hyuga Mirai, "White Snake Sage mentioned that you mastered Sage Mode. I didn't expect it to be so perfect. No wonder you focus only on learning sage techniques. So, did you summon me this time to learn the techniques of Ryūchi Cave?"
Hyuga Mirai continued walking, saying, "That can wait. I need to study your body first. Just lie down obediently later and give me a little blood and some tissue. That will be enough."
"What? Is that all?" Ichikishima-hime replied, then obediently followed him.
After bringing Ichikishima-hime to the laboratory, Hyuga Mirai began studying her body structure. The underground research space was large, and Shikitsuhima's form wasn't too big, so even when she transformed into her giant snake form, it didn't cause any problems.
After a series of scans and tests, and after Hyuga Mirai had Ichikishima-hime perform sage techniques over a dozen times, three days later, he had finally discovered a way to use natural energy to permanently enhance physical functions.
The method involved enhancing some of his internal organ functions to match characteristics found in Ichikishima-hime's organs. This way, after absorbing natural energy, Hyuga Mirai could filter it through his digestive organs, making other parts of his body adapt to the 'filtered' natural energy.
As for the physical modifications, Hyuga Mirai had already come up with several plans by the time the research results were finalized.
"Thank you, Ichikishima-hime. That will be all for now. Next time I encounter a frog, I'll definitely summon you."
"Well, it doesn't necessarily have to be for battle. If you go to the human world, you can also summon me there. It's been hundreds of years since I last visited the human world, and my clothes are already a bit outdated."
"I understand. Next time, I'll make sure."
With a soft thud, Hyuga Mirai interrupted Ichikishima-hime and quickly agreed, then dispelled the summoning jutsu, sending her back.
"Modifying my organs will need more caution. The plans I had earlier were too radical. I'll think them through again."
Perhaps due to the influence of Dr. Genus memories, Hyuga Mirai's approach to human experiments was more aggressive. However, since the final subject would be himself, he discarded many of the more extreme ideas.
"18, send me some test subjects—strong, with a chakra foundation, and preferably with a big appetite."
"Understood, sir." The calm, ethereal voice of 18 echoed in the spacious laboratory.
The last request might sound strange, but the stomach was an important organ in the modifications. According to Hyuga Mirai's plan, once he modified his internal organs to absorb and digest natural energy, he would be able to continuously absorb it. His digestive organs would convert the energy into harmless natural energy for absorption.
Hyuga Mirai suddenly had a realization: "Hmm, this feels a bit like a familiar technique..."
(End of Chapter)