(Yugao's Point of View)
Yugao stayed near the entrance of the cavern, perfectly content with watching from a distance.
The fight had been favorable for Kamui all things considered. The beast seemed limited to abilities inherited by the core. It rampaged solely on instinct and lacked much if any viable strategies.
The part that surprised everyone, including her, was the beast's sudden change in demeanor and use of that powerful chakra-laced scream. The part that shocked Yugao specifically was how she lost control of herself during the process. Her body seized up, as if run through by an electric current. She wasn't literally being petrified, but the effects were similar.
From the looks of it, Kamui was affected too as the beast seized that opportunity to strike. Seeing that, Yugao had wanted to immediately help her student, but she was still shaken by the scream herself. By the time she regained control of her limbs, Kamui's clones had not only broken free of the bindings but made the counterattack that concluded the engagement. From Yugao's perspective, it was this point that validated Kamui's earlier feeling that this fight was better handled by herself, who had special characteristics. With this, Yugao knew that, if she was out there with her student, the beast would likely have targeted her as well in that surprise assault and she wasn't a jinchuriki-type fighter; she didn't have their regenerative capabilities.
Yugao also concluded that they may be delayed in their mission should Kamui need time to heal her arms. She'd have to ask the girl herself, but a blow like that surely dealt significant damage to her.
She noticed that her student once again showed a supernatural proficiency with the elements. For Kamui to pick up steel release after only seeing one person use it and then perform a combination jutsu with her scorch release was unreal to say the least. That would be an interesting topic they'd have to train on when they got back to the village. The number of team-based tactics they could devise would be endless with the number of combination jutsu the girl could perform.
Funnily enough, Kamui using wood release wasn't that big of a deal in this situation. Yugao had long suspected her student to be capable of the feat, especially with the odd-colored wooden tools she's been using since the start of this mission. The girl made it very clear that she felt powerful enough to handle the ramifications of revealing the art, an assumption Yugao agreed with.
Now, Yugao was currently watching Kamui stare down the beast with her sharingan, having long since moved on the next stage of her plan. It had been quite a while since they had started, but there was no movement between the two aside from the gust of wind generated by one of Kamui's nearby clones to direct the poisonous blood vapor away from them.
In the exchange, Yugao hadn't noticed Kamui's life threatening position. Kamui's body hadn't changed overtly, and she wasn't close enough to see the movement of the girl's pupils nor had she seen the subtle twitches of panic her body gave off during the event. Like Kamui, she too had let her guard down when the beast was restrained. As soon as eye contact was made, she relaxed, completely missing the struggle.
At some point in the stare down, Naga's body had healed enough to stop releasing poisonous mist, which helped assure the group. Regardless, Yugao remained vigilant, worried that the beast could strike her student while she's in Naga's mindscape.
Then, it happened.
Slowly, the wooden bindings loosened their restraints and retracted back into the ground. In one of them, a shining blue light passed from Naga, traveled through the wooden tendril and passed into Kamui.
Quickly, Naga's hair snakes surrounded her to form a sort of makeshift cocoon. There didn't seem to be any obvious openings to see what was inside, but Yugao assumed that Kamui managed to save her in some way.
'What the hell?' Yugao thought, watching the event unfolding before her eyes. 'What did Kamui take from her? Is she turning back into a human?'
Suddenly, silvery-white tree roots wrapped around Kamui as well, forming her own cocoon. Progressively, the roots started radiating an increasing concentration of silvery-blue mist, something she hadn't seen them do before. Everywhere the mist passed, small grasses grew at a rate visible to the naked eye. It wasn't any phenomenon she had ever seen, even from Konoha's current wood release expert. She had read that the first Hokage's wood release could do something similar but had always assumed it to be a myth.
"Kamui, what the hell's happening!?" She loudly asked, needing to know whether this was intended.
Hearing her question, the closest clone turned to her and opened her mouth to explain before suddenly vanishing in a poof of smoke along with her other clone counterparts.
"Kamui!" Yugao exclaimed, worried that something unexpected happened to her student. She remained in place though. Even if every fiber of her being demanded she check on her student, there were still traces of poisonous mist in the air, something she was a lot more susceptible to than her student. That said, if it weren't for the cocoon being made of Kamui's own wood release roots, then she would've risked everything to pull Kamui back regardless of the consequences.
Frustrated, Yugao slammed her fist against the nearby wall.
"Dammit!" She roared, frustrated at her inability to help or even know what's going on.
'You're telling me everything when we get back Kamui. Everything!' she thought furiously.
Kamui's Mindscape (Kamui's Point of View)
Kamui stood in a world of stars. Everywhere she looked, she could see the night sky. Looking down, she realized that she was only standing on a small translucent platform of chakra.
"What is this?" She asked herself silently, confused on how her inner world could undergo such a change. Were these the renovations Yume described?
The empty void of stars differed so greatly from the paradise she had come to know that she had a hard time getting a grasp on the situation.
"This is space. Well, it's really an empty void for the most part. The stars are just visual illusions now, but that's temporary." A melodic voice replied behind her.
When she turned around, she noticed it was Yume, who looked the same as the last time they met. The only difference was the three sets of horns growing on the sides of her head. Their color and appearance looked like finely cut Sapphire. The largest set was on top, looking like a set of three-clawed talons that curved at a 90-degree angle upward with the tips slightly curving out. The middle set was shaped into a wide upward curve, while the bottom set was similar, but suddenly curved down midway.
"Wow… I have to say. I really appreciate the changes. Well, your change at least." Kamui commented in appreciation.
Yume shook her head in mirth.
"Not my changes Kamui, ours." Yume replied with mirth, a mirror of water appearing next to Kamui. "Look." She said, pointing to it.
Looking at the mirror, she noticed that she indeed looked like Yume, just younger.
Looking at Yume skeptically, she asked, "I love the horns, but they might be a bit of a problem when we return to the village. Are they permanent?"
Chuckling in amusement, Yume replies, "They are permanent, but you probably won't see them on the outside for a while. For now, you're probably wondering what happened to your inner world, correct?"
Kamui nodded. It's probably the best result she could hope for when considering the changes Naga had to weather, especially when she absorbed a similar serpent's core.
"Well, it's right over there." Yume stated, pointing in the distance.
Squinting her eyes, Kamui saw a small island holding a 25-foot-tall tree with bark shining in an iridescent silvery-white and leaves the color of her new horns hanging on its branches. Its roots were strange though. At the bottom of the tree, there were five different colored spheres, each about 3 feet in diameter. Inside of each, she could see a field of one of the five basic elements with all five represented in the combined group. At the top layer of the tree, two spheres rested; one of them was black, while the other was white.
The island was surrounded by a vast clear pool of translucent water filled with iridescent silvery-white lotuses, each of which produced motes of light that shined in a vast spectrum of colors. The pond seemed still and surprisingly didn't pour off the side, despite there being no border between it and the floating island's edge.
"It's beautiful..." Kamui muttered, causing Yume to smile with pride. "What happened here? Why the change?" She asked.
"Originally, the interior hadn't changed too much since the last time you'd visited except for the creation of this pond and the prototype for that tree. I was able to improve the quality of your mindscape, but I lacked a critical component for the most important change, one we've just acquired in spades." Yume explained.
"The core?" Kamui asked skeptically.
Yume chucked and looked toward the tree.
"It wasn't the core itself. That just influenced the direction of the change. As soon as the core entered the world, it started integrating into the mindscape. Despite Orochimaru's original thoughts on the matter, the core belonged to a water-based dragon, specifically one filled with tremendous amounts of life energy or yang chakra for what I'm about to discuss. It being a dragon was the reason it didn't react to anyone but you. Us being of a similar nature allowed for the resonance.
"The most important component in that core was yang chakra. Despite the vast sea of chakra you possessed, it was too heavily aspected to one side of the spectrum. To give context, we had the yin half of the original dragon god from your predecessor's former realm fusing with the yin half of Kurama. That posed a significant problem to your future growth. The most obvious sign is a much slower rate of development, both physically and mentally, than originally expected. To solve that problem, we needed to assimilate something that produces a powerful yang chakra of a similar quality to Kurama's Yang portion. It didn't need the same quantity, but we needed enough to draw out your true power." Yume replied.
"What do you mean? I haven't had any problems learning anything that I put my mind to or improving my strength at astonishing rates. What wouldn't we have been able to do? I can even use wood release, a release known for its life force requirements." Kamui asked, still skeptical about all of this.
"Kamui, remember what the ultimate goal of the inheritance process is. It's not to be a powerful human; it's to turn you into a divine beast, a successor to your predecessor's legacy, but even that wasn't the full truth. Really, it's to bring you closer to her predecessor, the dragon god, as that was her goal before the incident that led to her passing. Regardless of which we were pursuing, you needed life energy to build the powerful body needed to drive your divine mind.
"As a human, there's a limit to what you can do. Your mind can only comprehend so much in your current vessel. Even if you were satisfied with that, look at what happened to your arms. They wouldn't have taken any damage in that fight if we had this component before. The injuries you sustained can be attributed to your fragile human shell, a weakness that's being corrected as the integration changes your body, which will take a couple of months by the looks of it.
"You could argue that I was the one who suggested to restrain your growth, but that was in full knowledge of a human body's limitations. Your brother Naruto, for example, didn't have the same restrictions due to him possessing immense levels of inherent vitality and serving as Yang Kurama's container. He just didn't train as rigorously or efficiently. If he had the incentive, he could have already been your father's equal in physical prowess.
"Regardless of how powerful your chakra is, it'll always be limited if your body can't handle it efficiently. It's like a near-infinite well; a difference in the vessel is comparable to the difference between a bucket and a pump.
"To give more relevant context, there's one thing you have to know about the Uchiha. The source of your clan's power has always stemmed from a tree. The God Tree's eye is what every Uchiha carries the embryonic form of. The Senju carry its life force, while the Uchiha carry the eye. The closer your genetics and chakra resemble the original ancestor, the more of its powers you can express. For the Uchiha, this is represented through the evolution of the eyes. Your clan's eyes evolve into the sharingan, then the mangekyou sharingan, the rinnegan, and finally, the rinne sharingan. Even though you'd expect the rinne sharingan to be the yin component, it's actually a balanced combination of both. In short, you can't achieve the pinnacle level without a balanced chakra pool." Yume clinically explained.
Pausing for a moment, she looked toward Kamui's widened eyes to gauge her reaction. She had been waiting a long time to tell Kamui all of this but hadn't really seen the point. There wasn't much Kamui could do to solve the problem until she was at least a jonin, a rank that would allow her to search for sources of yang chakra potent enough to fix the new problem. What Yume hadn't told her was that their predecessor hadn't realized this problem due to a lack of knowledge of the differences between the two world's energy systems and therefore, hadn't accounted for it when creating her. Yume had only realized it after reviewing the new memories gained from Indra and Kurama.
Realistically, Kamui should have fully been a divine beast in human form by now, but she wasn't. There simply wasn't enough life energy to fuel the transformation. They had an ocean of spiritual energy, but no excess life energy to fuel the evolution. It was extremely frustrating for her as she couldn't finish her integration into Kamui until her body was fully transformed.
Seeing the confusion in Kamui's eyes start to fade into understanding, she continued, "Due to the nature of your inheritance, you can't perform a full regression to achieve the rinne sharingan of old, nor would we want to. Instead, I've been working on creating the form of a new Shinju, one created in our image without the baggage that would come with a normal regression. Before this, I created the prototype, but it wasn't alive. Even though you could use it as a base for wood style, it lacked the vitality the first Hokage was known for. It would have been a good conductor for elemental attacks but would not have been able to reach its full potential. Once the first streams of vitality integrated into your core, the prototype came alive almost immediately. That's what this is, the beginnings of a God Tree and the initial stages of the ability it automatically drew from your DNA, 'Amenominaka'.
"From Indra's memories, his father explained that Kaguya Otsutsuki could create multiple physical dimensions in the real world and move between them at will. Amenominaka was the primary ability responsible for that. This new Shinju awakened it the second it came alive and activated it immediately with your inner world as the core dimension.
"The reason why the world changed so drastically is because of Amenominaka's effects. The previous world was one of imagination, a reflection of who you were; now, it's becoming real." Yume finished her explanation, internally excited at the potential utility this ability would grant her host.
Silence reigned between the two for a moment as Kamui considered everything she had learned. This was a lot to take in at one time. Normally, she would have preferred to receive this information over time, rather than in one large lump sum.
"Ok…" Kamui started slowly. "Of all of this, what has changed immediately? Where is all the chakra that was here before?" Kamui asked, deciding that she would consider the implications after she'd finished the mission. Right now, she just needed to know what's different.
Yume nodded at her host's frame of mind. Rather than try absorbing this new information now, she'd probably go over it again in her head once she returned to the village. The good thing about being an Uchiha is the perfect memory that came with it. Well, that could also be a curse, like it was in the case of the recent memories Kamui just received; but for situations like this, it was a godsend.
"First, your available chakra pool has gone down significantly. As you're aware, your chakra pool was always separated into an immediate pool and a separate condensed pool resembling a sealed tailed-beast due to your chakra network not being able to support the full amount. For the immediate future, the larger pool will be unavailable for your use. You'll be limited to the level of an upper level jonin. Basically, you'll probably only be able to make one reinforced shadow clone per fight and still have enough chakra for other higher-level techniques. If it makes you feel any better, that's the amount of chakra you would've had by this point if we hadn't swallowed Yin Kurama nor had this yang chakra source. Your perfect chakra control is going to be really helpful for a while.
"This restriction's not permanent, but I'll need the chakra in here to continue the development of the tree and dimension. It's an interesting situation; they exist both as your inner world and as a physical dimension. Then, you have those spheres attached to the tree. Those appear to be their own sub-dimensions as well. I'll explain the specifics later, but I'll need a lot of chakra for their continued growth. Especially with the tree, the more things develop, the stronger your ocular abilities and connection to the world will become; the latter should help with your elemental sense training immensely. If I were to guess based on how everything else has went, you'll probably gain access to abilities in stages as this world is created. At least, that's how every other ability in your bloodline has been structured.
"In the event of emergencies, I can let you use more chakra, but in this unstable development period, I really do need it here. Technically, we could use natural energy, but that wouldn't be good for the tree's development. We want the tree to be entirely composed of your own chakra. It'll allow a full synchronization between you two."
Hearing this, Kamui sighed in frustration. Chakra capacity was never a problem for her, so hearing this new restriction sounded like it would be a pain to deal with. Well, it would've been a pain for her brother who was basically a leaky faucet. She should be fine though. The only problem lied with the fact that teleporting to and from mission sites no longer sounded as viable as it used to be. Teleport costs went up by distance, so long-distance traveling was bound to be expensive. She just didn't know how expensive due to it never being a problem before. Either she'd need to limit her long-distance travel plans, or she'd need to come up with an alternative.
"How long will this take? I don't mind working with a handicap; I don't use much more chakra than that anyways unless I'm either training or teleporting. It does put us at a higher risk though." Kamui asked with mild frustration.
"I honestly don't know. Truthfully, it could take a few years, but the rate of development will likely increase proportionally to the integration level of the blue core. The more life force you're able to generate, the more effective your chakra will be in the development process." Yume explained, uncertainty prominent in her tone.
Kamui let out a profound sigh and shook her head.
"Is Amenominaka part of my mangekyou sharingan? Was that awakened too?" Kamui asked, a budding hope rising in her chest.
Yume crossed her arms and looked down in contemplation.
"How do I explain this properly...? Well, I'll put it to you straight. Your eyes are different than the rest since the mangekyou exists as a separate component rather than being another stage in a linear line of progression. The problem is that the mangekyou only partially awakened and not in any useable way. So far, only Amenominaka awakened and that's currently being built, so it's not actually usable. Basically, no. It's still being developed. That's the problem with awakening Amenominaka specifically. If it were any other ability, you would have access to something, but Amenominaka needs to be built before it can be used. At least in your case, I'm here to guide the building process while you handle your training and shinobi responsibilities." Yume replied carefully.
The explanation required a great deal of care to help her host fully understand the situation as it's never happened before in the clan's history. Even Indra's memories don't have records of Kaguya taking additional time to build her worlds. Her current guess was that either Kaguya didn't explain anything to Hagoromo, or the god tree built them itself while it was growing. Kaguya merely inherited it when she ate its fruit. The latter option made more sense based on her recent experience. This new tree pretty much grew on its own and Amenominaka is guided almost entirely by it. She only gave occasional directions to ensure the tree knew what it was doing. This bloodline their predecessor chose is weird to say the least. To think that a naturally occurring semi-sentient soul could be born from one's own chakra and bloodline.
"So, in the short term, I have no mangekyou, a heavy restriction on my chakra pool, and a better connection to nature energy. Did I miss anything?" Kamui summarized, rubbing her temples to sooth her growing headache. She was a little bummed that all this cool stuff started as restrictions, and she hadn't even gotten a usable mangekyou yet.
'Oh well. At least the ability will be cool when it's done. From the sounds of it, I might even be able to use this place to train when I reach a certain point. There's a lot of utility a place like this can provide when it's mature. I'll just have to be patient. I wonder what the other ability will be when I fully awaken it. It's sure to be an exciting couple of years watching it all happen.' She thought, trying to be positive, despite being introduced to this at too early a stage to be as excited as she wanted to be. As negative as her thoughts trended to on this, she really was excited at the prospects; she was just on a mission and had to consider the new limitations first.
"That's correct. Now, you better get back to the outside world. You've been in here for the past few hours and your sensei's probably getting worried. We'll have plenty of time to discuss this later." Yume advised.
Kamui nodded, not too surprised that there was a dormant period. She was just glad that it was relatively short.
'Next time, it might be a good idea to see if I can quarantine the item before integrating something, especially during a mission.' She reflected, realizing that she was a little hasty in letting that thing merge with her. Even if it worked out, she recklessly assumed that, since Yume didn't stop her, everything would work out; it did, but it was still extremely reckless.
"I don't say this enough but thank you Yume." Kamui gratefully stated, receiving a nod of appreciation from Yume. With that, Kamui allowed her consciousness to return to her body, causing the astral body here to disappear.
Seeing Kamui return, Yume muttered, "No, thank you Kamui. I just hope I can complete this space before 'she' awakens, though I highly doubt I'll get that luxury. From what our predecessor sensed when she arrived in this world, we need this power or we'll die without a prayer, not that it'll do you any good to know that right now. Leave this part to me." She muttered, looking down at one of her hands, which showed barely noticeable traces of fading.
This was why I didn't mind giving Kamui Yin Kurama's chakra despite it being too overpowered for someone with her level of chakra control. Building dimmensions would take an enormous amount of chakra and time, which that pool can contribute to. It may seem like a nerf, but it's really not. All it'll do is change some of her tactics in the field. There are a lot of possibilities for one with her diverse skill set.