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

Like every day Yuna woke up very early. The combination of her bloodline and Kurama's chakra heavily reduce her need for sleep, making it possible for her to only sleep about 4 hours and still be well-rested. Like every morning she went through her usual training routine. She floods her whole body with chakra stimulating every single muscle in the body while simultaneously keeping tight control over every single bit of chakra in her system. An absolutely insane exercise that trains both her Chakra control and her body.

After an hour, with her whole body completely drenched in sweat, she stops the exercise and instead spends some time meditating to increase her spiritual energy. If a normal 3-year-old went through that kind of routine every morning she would probably end up crippled by the age of 11, but how could Yuna consider be a normal 3-year-old? She has perfect control over every aspect of her body. She had hundreds and thousandth of years of experience in training her body. She knew exactly how far she could push herself without dealing any permanent damage to herself.

'Well, time to get us a flat to live in. Might as well make a trip to the library to get more information about the village. I also need to do some research of what is currently popular for my money-making schemes.'

Just as Yuna finished sorting her thought's a still sleepy-looking Naruto entered the room.

"Morning, nee-san."

"Oh. Good morning Naruto. Ready to learn your first Jutsu?"

That immediately woke him up.

"Yes, yes, yes. Show me how to do it nee-san"

Just when Yuna was about to start the explanation however someone knocked on the door.

"That's probably breakfast. Let us eat and then we can start."

Yuna quickly transformed into her adult form to receive the breakfast and opened the door. After a quick breakfast, Naruto was eager to start learning his first Jutsu, so Yuna quickly started her explanation on how it works. Unfortunately, a big problem came up.

"Nee-san what's a chakra?"

'Damn, I forgot about that. I don't think the explanation will be much help for Naruto. Maybe I can just inject a little bit of chakra into Naruto so he understands what it feels like?'

[By the way, didn't you say you will start his training when he's 5?]

'Oh my, to think you would care about another human. I'm so proud of you.'

[*Snort*]

'As for Naruto's training: I've decided to at least start teaching him some method to improve his chakra control. Since his reserves increase at the same pace as my own it becomes harder and harder to control it. If I were to start teaching him at age 5 it would be a lot of work to reach a decent level.'

[Didn't you say your method is too complex?]

'It is. That's why I came up with something simpler.'

"Ok Naruto, just close your eyes and try to feel something moving inside your body. I will inject a little bit of my chakra near your stomach. Try to concentrate on that place"

Although it took a while, about an hour later Naruto managed to get a feel for his own Chakra.

'As expected of my little brother, he is a genius.'

[Do you even know whether that was fast or slow?]

'Nope, no clue'

[…]

"Good job Naruto. Learning how to create and move your chakra is the first step in becoming a ninja. Do you want to give the Henge a try now? Remember, push the chakra into the ram seal and imagine what you want to transform into."

"Okay, nee-san I can do it!"

Naruto slowly started to go through the correct hand seals and then started putting his chakra into it. Massive amounts of chakra started leaking out of Naruto as he tried to inject it into his hands.

'That's around 50 times as much as necessary huh.'

[Not really surprising. For the two of you that is still just a drop in the ocean]

'That's true. Considering how little chakra this needs it will probably be pretty hard for Naruto to learn to use this jutsu efficiently.'

A few seconds later a smoke cloud appeared and then disappeared to reveal Naruto having transformed into… something.

It somehow could be considered human-looking. Well, it had 4 limps and one head at least, however, the proportions were very off. On arm was significantly bigger than the other two. Yes, the other "two". One of its legs became an arm somehow, while the face looked like someone pressed random during the character creation.

Naruto quickly noticed, that something felt off and canceled the transformation. He immediately felt disappointed in himself for not doing it correctly, but those thoughts were quickly stopped when he heard Yuna chuckling.

"What, you thought you would just get it at first try? This is actually one of the jutsus you need to know to graduate from the ninja academy. You have already been able to transform which is actually pretty good. Now you just need to work on imagining what you want to transform into. I would advise you to start with transforming small parts of your body first before trying a full transformation"

Naruto couldn't help but blush a little, after all, he really thought he would get it on the first try. He, however quickly recovered when Yuna started praising him and gave her a happy smile, but then he noticed that something seems to be off. After thinking about it for a moment he realized what the problem was.

"Nee-san you said it was something ninja's need to graduate, but can't you already do it perfectly."

"Haha, that's because your nee-san is a genius."

[You are truly shameless.]

'What else am I supposed to tell him? I might tell him about my past life one day, but certainly not while he is just 3'

[Fine, whatever, but I still pronounce you as completely shameless no matter the reason.]

'Well, can't really deny that can I?

"Amazing! So nee-san is a genius"

'Sigh my cute little Naruto is so pure. I need to make sure he doesn't get corrupted.'

[Aren't you the greatest source of corruption?]

'Shut up, stupid fox. No one asked you.'

[Oh, getting angry because you know I'm right huh?]

'No comment.'

"Naruto, there is a good training method you can use that will make it easier for you to learn jutsu later on. Are you interested?"

How could he not be interested? He started eagerly nodding his head.

"Of course, I want to know. Teach me, teach me!"

Yuna quickly prepared an empty bowl and filled it up with water. This was the chakra control exercise she came up with.

"Ok Naruto. This is what you have to do: I want you to cloak one of your fingers with your chakra and then dip it into the water. Your goal is to protect your finger from getting wet while generating as few ripples as possible."

Yuna quickly put some chakra into her finger and then dipped it into the water. After stirring the water for a few seconds, she pulled her finger out and put it onto a nearby piece of paper to show that it indeed wasn't wet.

"After you learned how to do it add more of your fingers until you can do it with your whole hand and sooner or later you can do something like this"

This time Yuna cloaked her whole hand in chakra and put it back into the water. This time however she grabbed the water and took a big bubble of water out of the bowl. Holding it in her hand like it was a water balloon.

"Pretty cool huh?"

"AMAZING! So, I just need to train like that, and then I will be able to form a water ball like this?"

"Correct. However, this is not easy so don't be discouraged if you can't do it quickly"

"Haha, alright I'll do it"

'How to make a young child go through a tedious and boring exercise? Show him something fun he can do with it.'

[Are you a Demon?]

'Funny thing for you to say, mister Demon Fox'

"I will be going out for a while Naruto. I still have a few things to do. I'll be back for dinner."

Naruto only gave her an absentminded nod while trying to concentrate on coating his finger in chakra.

'Well then, let's solve the problem of our living arrangements, shall we?