Retro talking me into doing this: a full defense and explanation of Hinagiku's speed jutsu.
The first time this technique was used. Jun 22, 2018. Over two years ago. Honestly, I'm not sure why it's an issue now, but nevertheless let's get on with the explanation. It is right there in the Post, but I'll go in-depth with even more specifics and why Hina is able to perform these techniques without hand seals.
Component 1: Lighten-Weight Rock Technique
The first component of this three-part technique is the lighten weight rock technique.
https://naruto.fandom.com/wiki/Earth_Release:_Light-Weight_Rock_Technique (Earth Release: Light-Weight Rock Technique)
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That's what the Naruto-wiki says about it and here's it being used in canon:
You may take note of the complete lack of hand seals required to perform this Jutsu. Also, as we can see from Akatsuchi and Kurotsuchi, this technique doesn't require the user to constantly be in contact with whatever they're lightening or constantly be channeling their chakra. It is a one-time thing. You touch—Boop!—and your weight is reduced. This is further supported by Onoki being able to utilize Jutsu while this technique is in effect, such as using Earth Release or Particle style while floating.
Second Component: Instant Water
Now that her weight is reduced, its time to apply some speed. I chose to use the Second Hokage's Instant Water technique. This isn't a technique that exists in canon. It's actually a move taken from one of the Ninja Storm games.
https://naruto.fandom.com/wiki/Instant_Water (Instant Water)
Here's the wiki entry:
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Employing their mastery of Water Release, the user releases a wave of water below their feet to act as jets to increase their speed which allows them to dash towards the opponent and attack with a full-body blow.
So the user released a wave of water from their feet to propel them forward.
This technique also doesn't utilize hand seals.
Component Three: Wind + Water Harmony
If you look at the Wiki page on Water Release, when they start speaking about what natures go together with Water Release, they mention Wind Release can be used in conjunction with Water Release to churn the water. You can look at the full entry below:
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So Hina's modification to the Instant Water technique is to also expel jets of air that increase the power of the water jets. Hence why it's ingeniously named Instant Water Gale.
So those are the three techniques used to create Hina's speed-boosting technique. They're each very simple individually and none of them require hand seals to utilize. The last one isn't even a Jutsu on its own.
To clarify, although this uses three different Jutsu and three nature transformations in total, it does not use all three of them simultaneously. As I pointed out in with Akatsuchi and Kurotsuchi, once your weight has been lowered, it will remain lowered for at least some time. It does not require you to constantly be channeling the Lighten Rock Weight technique. It's a one-time thing.
After her weight has been lowered the only thing Hina needs to do is expel water jets and enhance their force with her wind release. She uses these wind-water jets to throw around her light-weight body and thus achieve extreme speed. That's two simultaneous nature releases.
That expulsion is, however, made easier by The Hyuga Clan's secondary kekkei genkai. Namely, that is the ability to innately expel chakra from all their chakra points. I don't think the Hyuga's ability to expel chakra from any part of their body should come as a surprise to anyone. Hina merely uses this kekkei genkai to enhance her usage of this technique, because expelling chakra comes easier to her than it would to other Jonin.
I'd point out that she hasn't even been using that kekkei genkai. She hasn't used it to expel wind-water jets from her back or hands or wherever to give herself more boosts; and, I'd argue she would certainly be able to do that given:
1) Her kekkei genkai enables this
2) None of these jutsu are complex enough to require hand seals
So far, she'd been using this technique like a completely normal Jonin would. So you could say she isn't getting any benefit from her kekkei genkai.
The only argument I can really think of in which the Hyuga kekkei genkai is used to any effect is where you postulate that because HIna can innately expel chakra, she only needs to focus on the two nature transformations and less of the shape transformation.
Individually the techniques aren't much but after stacking three of them together the speed boost should be fairly substantial. The logic behind it is high-school level physics.
F = ma
Force = mass x acceleration
We can re-arrange the equation to show:
acceleration = Force / mass
This means two things:
1) Acceleration increases as Force increases
2) Acceleration increases as Mass decreases
The Wind-Water jets provide an increase in force, and the lighten rock weight imitates a decrease in mass.
Now, I remember some arguments like...she should logically only be able to move as fast as the water, but now that I've got a clear mind I realize that the above physics of the technique easily debunks that. Her movement speed as nothing to do with the speed of her jets, but instead everything to do with the Force of those jets and the functional Mass of her body.
If you hit a ball with a bat, the ball does not go flying at the speed of the bat-swing. Its speed is dependent on much more complex calculations. The force of the swing will continue increasing the ball's acceleration until external forces like air resistance and gravity reduce that acceleration to zero. Only when the acceleration is zero has the ball reached its peak velocity or speed, and afterward, the outside forces continue to work on the ball causing it to slow down.
Breaking the Sound Barrier: becoming Super Sonic
Is the sound barrier that hard to break? In the real world, yes. In Naruto? No.
I do have reasons for why I believe that as well.
1) The speed of sound and supersonic speeds are just...not much in the Naruverse. If you want to accomplish any kind of character scaling you need something to work with and when we use real-work physics to try and scale things, we find out that supernaturally gifted characters are, in fact, supernaturally gifted. By Shippuden, everyone is casually breaking the sound barrier.
This is Hebi Sasuke dodging a C1 explosion.
I'm going to start using some assumptions here and we're actually going to downplay Deidara's explosives a lot. We're going to do him dirty and say Deidara's explosives are about as strong as Black Powder.
Black Powder is what they used as early gun-powder. It's what they used to fire flintlock and matchlock pistols back in the 1700s and ish. So in this scenario, Deidara's explosions are only about as good as gunpowder from 200 years ago.
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The bullet fired from such a gun, can reach speeds ranging from 120 m/s to 370 m/s. This is notable because the speed of sound is only 343 m/s. So at the high end of the spectrum, we have bullets that could break the sound barrier. However, Deidara isn't firing any bullets, so what about the explosions itself?
So the explosion itself would be near twice the speed of sound and both Sasuke and Deidara still evaded it pretty casually from nearly point-blank, literally inches from them.
Let's look at a C2 bomb, one of the land mines Deidara had that Sasuke dodged from point-blank as well.
He avoided the blast by flying up.
Personally I think Deidara's explosions would be much stronger than black powder and thus have higher detonation velocities, but even if we spit on Deidara and say his explosions are only as good a black powder, the speed of sound is just something characters consistently go above.
For the record, if Deidara's explosions are similar to TnT, then TnT has a detonation velocity of a bit over Mach 20.
2) The Rotation itself is a technique that touches upon the sound barrier
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That's not quite the speed of sound, but if a genin can do that I think a Jonin can probably breach the speed of sound with their rotation. I think that escalation is reasonable. So if a genin can use their chakra to push themselves near the speed of sound, I think a Jonin like Hina can use her chakra to push herself very comfortably beyond the speed of sound.
Conclusion
All of that said:
I do believe the combination of these three techniques should do well to push a Jonin, dare I wank her and say near-Kage-level, into super-sonic speed. It's the same principle behind what enables a bullet to be pushed past the sound barrier. Something very light is launched with a lot of force and thus goes very fast.
I simply fail to see why a Jonin would be unable to push herself into the super-sonic range with her chakra.
There was a lot of contention about her requiring hand-seals, but none of these Jutsu require hand seals. You can develop Jutsu specifically designed to work without hand seals and if anything the Hyūga kekkei genkai should allow her to expel chakra more easily.
Sagiso's wind shadow is also simply chakra expulsion. It's very violent chakra expulsion, but the basics remain the same. Sagiso expels chakra to push herself faster. Her sheer speed is because she does it so violently that it damages her legs in the process. The trade off is speed for self-injury.
Hinagiku should need no effort to achieve Sagiso levels of speed with her chakra, and that's without jumping through all the hopes of adding on two additional Jutsu to simple wind expulsion.
While I do appreciate the explanation, there are many concerns with this combination to gain its results.
1. The water move without handseals evidently only exists in a game, which everyone got on about me using the wind justu on Sakon from a game until I could dig it out from an anime. Not to mention her somehow learning a justu specific to the second hokage without and training of his AND somehow modify it as well.
2. Deidara and sauske are currently over the bar of every jounin here. They aren’t good bars for this. Not to mention it’s difficult to see what’s an ‘anime effect’ and what’s a ‘feat’ especially since Deidara has the whole hiding in explosions shenanigans.
3. So you want to boost her to Kage level just to keep this technique...?
4. Realistically as well, this technique wouldn’t work in the first place since due to being miniaturized your small body would shatter upon the force of going that fast, saying you don’t even hit the slightest obstacle along the way. Not to mention even if you were somehow hardening your body’s defenses, you wouldn’t be able to turn due your now minuscule muscle mass to counteract the force.
5. Without handseals is the problem. The argument was you can do all of this with emissions. Which is just ludicrous. You actually have to preform justu for all of this, not emit the justu from your skin like sweat.
Theres just many issues upon issues with this skill in it’s current state. So I’d suggest workshopping it like we came to that conclusion last night.