Goddess of Ice; Reborn as Naruto’s twin sister [Completed]

In a meadow, deep inside the forest of the Land of Waves a young girl was laying in the grass and was seemingly asleep. This girl was, of course, Yuna Uzumaki, but rather than being asleep, she was in deep meditation.

Inside her mindscape, a huge fox, Kurama, was sitting cross-legged with the palms of his hands put together in front of him. On top of his head sat a mature beauty who seemed to be in her late twenties. She seemed to be a mature version of Yuna and she was sitting in the same position as Kurama, as well. This was how Yuna's soul looked while in her mindscape if she didn't try to conceal it.

Occasionally, a wisp of red violent chakra would leave Kurama's body and enter into Yuna's, while a wisp of blue soothing chakra would occasionally exit Yuna's body and enter Kurama's. This was the process of removing the corruption and hatred from Kurama's chakra. Yuna has started this process after the two Kurama's got back their Yin-Yang balance and, naturally, taught Naruto how to do it as well. The further Kurama's chakra was refined, the easier it would be to use and the purer it became, the more it would increase the duo's strength.

Like that, Yuna and Kurama spent the whole night refining more and more of Kurama's chakra.

"Guess that's it, for now. Someone is approaching me. How are you feeling, Kurama?"

[…Better. Much better. Like a burden, I didn't even know about, is slowly being lifted from me.]

Yuna nodded her head in acknowledgment. That was pretty much the expected outcome for her.

Meanwhile, in the outside world, a beautiful-looking young woman was approaching the sleeping Yuna. She had long black hair and a kind face. She was currently carrying a pouch that was filled to the brim with all kinds of medicine. She, Haku, is the hunter-nin that helped Zabuza fake his death. 

After she came a bit closer to Yuna, she noticed the Konoha headband that Yuna had tied to her upper arm and for a split second, some killing intent leaked out of her, but as soon as it came it vanished.

Haku reached forward with one of her arms in an attempt to wake up Yuna, but before she could do so, Yuna spoke while her eyes were still closed.

"Can I do something for you?"

Although Haku was startled by Yuna actually being awake and hoped that she hadn't noticed her killing intent, she still answered with a kind smile on her face.

"I was just curious why someone was sleeping in the middle of the forest. May I ask what you were doing here this early in the morning."

Yuna shrugged her shoulders and answered.

"Getting some training done. And what about you…"

Yuna opened one of her eyes and quickly scanned over Haku and ended up keeping eye contact with her.

"… Miss chunin?"

Haku's body shuddered a little when Yuna scanned her. She felt like all of her secrets were exposed instantly, but when Yuna actually called her a chunin, her eyes widened and she immediately jumped back and got ready for combat. Yuna, however, was still lazing around on the ground seemingly not even noticing the tense atmosphere.

"What is wrong? Why aren't you getting ready to fight?"

"Hehe, you are pretty decent at acting, but I can see your hesitation. You don't want this fight to happen right?"

Haku, however, didn't say anything and just prepared herself for a fight. Yuna couldn't help but roll her eyes.

"Look here, little girl. I have my own agenda and fighting you here doesn't fit it at all. If you get lost now, we can just forget this encounter ever happened, but if you force this fight…"

Yuna released the firm hold she had on her chakra, resulting in a massive amount of chakra flooding the clearing.

"…I am happy to oblige."

Haku almost staggered when she was hit by the presence of Yuna's chakra. She couldn't believe such a young girl could have such a massive chakra pool. She immediately lowered her weapons a little when she realized that this fight might actually end up fatal for her.

"What is your agenda?"

"Hehe, that is a secret of course, but if everything works out the way I want it to, I guarantee you won't be dissatisfied by it, either."

Although Haku very much doubted that, she wasn't exactly in a position where she could make demands. She quickly decided to retreat for now and tell Zabuza about her encounter. Someone as powerful as Yuna will be an important piece in the following battle.

"Seems like you made the correct decision. Guess I will be taking my leave then. I don't think you can calmly collect herbs while I am nearby. Oh! The name is Yuna Uzumaki, by the way. You should probably write it down. It will become important in the future, haha."

"My name is Haku. I am not looking forward to meeting you on a battlefield, but will still fight you if I have to. Oh, and by the way. I am actually a boy."

Yuna only scoffed at that last comment.

'Is she trying to throw me off balance with that supposed "shocker"? Guess I will have to counterattack.

"I see Haku, the boy. I am actually looking forward to a nice relaxing battle with whoever is coming after me, Haku the boy. By the way, Haku the boy, you didn't really think I would be laying in the middle of the forest without setting up anything to protect me, right?"

Haku was getting more and more annoyed by Yuna making fun of her like that, but when she heard Yuna's last question, her eyes actually widened in surprise. She quickly started to circulate chakra into her feet to get out of the clearing as soon as possible, but it was already too late.

*SPLAT*

Yuna gave Haku, whose face was currently completely covered with cream, another look, and couldn't help but chuckle a little.

'At first, I only did this to prank our so-called teachers, but this is getting more and more enjoyable. Hehe, but to think I would find myself an ice user. Since Zabuza was just a mercenary, Haku is probably the same. Both of them hold no loyalty to Gatou. Guess I have to do some moving behind the scenes to get what I want.'

With a small smile on her face, Yuna vanished from her position and started to follow Haku back to her base.

'I hope I can get my hands on some of Gatou's goons so I can get the information about his base out of them. Then a little bit of genjutsu here and a little bit of manipulation there and everything should work out how I want it to. It has been quite a while since I did a proper infiltration. This should be fun~'

In the meantime, back at Tazuna's house, Team Seven and Anko were currently standing at the edge of the forest. Kakashi had just finished demonstrating his "tree climbing exercise". Sakura and Sasuke were staring at him in wonder, Naruto's eyes clearly showed a look of "how is walking up and down a tree going to help me" and Anko was looking at him accusingly.

Kakashi noticed Anko's accusing look and could only cough awkwardly.

"I was focusing on team building."

Although Anko still wasn't completely convinced, she gave a glance at Sasuke and Sakura and understood the problem to some degree.

Seeing that Naruto didn't seem to be convinced either, Kakashi spoke to him next.

"What's wrong, Naruto? You don't seem to be convinced."

"Yeah, I don't really understand how this could help us in the upcoming fight."

Kakashi thought back to what Naruto had done so far and nodded his head in understanding.

"Considering what you have shown so far, I assume you have already done this exercise before?"

"Well, not really. But I have been doing different exercises that nee-san has been coming up with for a long time now."

"Oh? That got me a little curious. Can you demonstrate one of them?"

Naruto, naturally, was happy that he could show off something his sister came up with and joyously walked towards a nearby patch of water.

'I see, water walking, huh? He already walked on water during the fight with Zabuza, but I thought he could do it because of Kyuubi's chakra coating him, guess that was incorrect.'

However, Kakashi's visible eye almost popped out when, instead of walking on water, Naruto grabbed some of it and held a ball entirely made of water in his hands.

Naruto hasn't noticed Kakashi's state of mind yet and happily started explaining some more details.

"It took me quite some time before I could even form the ball. After I mastered it, Hinata, Yuna, and I started throwing it at each other so we could get used to channeling precise amounts of chakra even while we were moving."

Naruto reeled back his arm and threw the ball against a tree that was quite a bit away from the group. The water ball impacted the tree with a boom that caused Kakashi's state of mind to deteriorate even further.

'What the hell was that? How is it still this stable after being thrown? Doesn't this look a lot like the [Rasengan]? Is that damn girl developing a [Rasengan] that can be thrown or something? No, wait! She shouldn't even know about the [Rasengan]! What the hell is going on?'

Kakashi glanced at Anko who was standing next to him and noticed that she only seemed to be slightly surprised by what just happened. He really wanted to ask her how she wasn't surprised by what just happened, but then he realized that Anko had already spent a full week with Yuna alone.

'I see. I guess her mind is completely shattered at this point.'

Anko felt that someone was thinking something rude about her, but decided not to bother about it. She couldn't help but be a little impressed by Naruto's chakra control.

'I thought only Yuna was abnormal, but it seems her little brother is quite the monster as well. Considering Hinata went through the same exercise I doubt she is normal either. Things are about to get really fun, aren't they? Maybe I should try out this chakra exercise, as well? Seems to have worked wonders for Naruto.'

A smirk appeared on Anko's face when she thought about restarting her training properly.

'It has been a while since I did some proper training, but I feel like things will get quite chaotic from now on. I would rather not be left on the side when things start to get really hectic. After all, the further you are in the chaos, the more fun you can have.'

Anko touched her cursed seal, and her face grew vicious.

'At this point in time, how could I dare not to trust Yuna with removing this? And as soon as it is gone, I can finally go all out during fights again. I can't wait!'