Corollary: Kakashi has exactly as much Chakra as the plot demands.

 

Chakra has to be actively produced, apparently. And your chakra control influences both how much chakra you spend on jutsu, and how efficiently you convert stamina into chakra.


Here's the start of ebisu's explanation: http://www.readmanga.eu/manga/1627/Naruto/90/4

Most fics just give people a big pool o' chakra to simplify matters.

 

That's come up a fair bit in recent chapters which should make for a decent reminder. I think at least 4 characters talk about building up their chakra.

Anyway, I had this one hammered out with help.

Rule Whatever: Yin and Yang chakra are created from a significant imbalance between physical and spiritual energy.

As chakra is created, the ratio between the physical and spiritual energy is dependent on the individual as defined by their personality, genetics and training. Some individuals generate chakra with more spiritual energy than physical whilst some are opposite. The ideal ninja would have a perfect balance between them. This is the same for the chakra that is constantly being produced within the body and the chakra that is deliberately generated. Most jutsu favour either physical or spiritual energy to some degree, depending on how they function, meaning that the energy ratio within the chakra needs to be changed when moulded to use the jutsu. The natural energy ratio of a person's chakra influences how easy or how difficult it is to use a jutsu. For example, Bunshin is a non-physical image so it uses spiritually-included chakra which is why Naruto, who’s burdened with the Kyuubi’s Yang chakra, struggled to learn it despite mastering Henge and Kawarimi.

It is only when the physical or spiritual energy composes at least 75% of the moulded chakra that it becomes Yin or Yang chakra. When there’s more spiritual energy than physical energy, it is Yin chakra. When there’s more physical energy than spiritual energy, it is Yang chakra.

Yin Release uses imagination and can bring form from nothingness e.g. genjutsu.

Yang Release governs vitality and can breathe life into form e.g. medical ninjutsu.

It's possible for this to be taken to extremes where the chakra is composed almost entirely of either physical or spiritual energy, causing it to become unstable and independently seek out its opposite form of energy to attain some balance. This is typically just a mistake made during training but some individuals have developed jutsu which use this as the main function e.g. Tayuya's Revolt of the Demon World.

Because chakra becomes unstable when the energies are so unbalanced, controlling such chakra requires special advanced training or unusual skill, hence why Yin and Yang Release jutsu either require very fine chakra control (genjutsu, medical jutsu), or the special training is a closely guarded clan secret (shadow jutsu, mind/body switch jutsu, body expansion jutsu).

Yin-Yang Release is an incredibly difficult art which uses Yin and Yang chakra together. It involves creating something from the user’s imagination (Yin) and then giving it life (Yang). It requires the simultaneous use of both chakras and only the Sage of Six Paths was known for mastering it, resulting in him possessing the ability known as the “Creation of All Things”.

Another Rule: Each element has their own unique traits that leave them suited for different purposes.

Fire: Flame-like high-temperature chakra that burns everything it touches to a crisp. It has the additional effect of setting the target aflame, and stands beside Wind as an offense-specialized style.

Wind: Blade-like chakra to behead, split and sever anything and anyone. Used with special ninja tools or in jutsu, it has the best offensive ability in close to medium range.

Lightning: Easy to diffuse, it has good compatibility with medium to long range jutsu. Infused into a metallic weapon, it adds harming and killing efficiency, as well as electrocution.

Earth: The Nature that alters everything in solidity and composition. If one masters it, it is possible to give jutsu or objects the resistance of steel and the flexibility of clay.

Water: A good compatibility with shape transformation. Creating a mist to hide oneself, or a tidal wave for confinement, it is greatly beneficial for supporting purposes.

(This all are copied from the third databook but I figure they're worth putting out there.)

 

I think Madara also used this? Have to go to sleep in a moment so don't really have time to look for the page (or comment on the other stuff, will do that tomorrow) but I am pretty sure Madara also created stuff like that. Maybe not at the level of the Sage, but he did create black zetsu and I think somekind of rod? It might be that someone who has awakened the rinnegan can do that kind of stuff. Or it could just be a case of Senju+Uchiha gaining some yin-yang abilities.

I do think its a bloodline ability of some sort and cannot be learned no matter how much one practises.

Danzo also used a crude version of yin-yang in the form of Izanagi. However that only made it possible for him to change the nature of his own body (avoid death) rather than completely rewriting reality and bringing things into existence out of nothingness which the Sage could do. That also required both Senju+Uchiha compoments (at the time anyway, not sure if its been retconned),

I would say its also likely that most of the "magic artifact" items in Narutoverse such as Itachis Totsuka sword and Yata mirror and ofcourse the sealing items of the Kinkaku&Ginkaku (actually confirmed) were created by the sage through Creation of All Things.

For fanfiction purposes, this would in theory allow bizarre objects to be used in a story since anything the Sage could imagine, he could materialize (though obviously anything silly would ruin a story).

Kinda makes you wonder actually why the Sage in canon never created any super-weapons for the purpose of defeating Juubi if it ever returned. I mean with Creation of All Things, he should have been able to basically imagine an anti-Juubi item and just instantly create it. Unless maybe the sealing items, Totsuka sword, Yata mirror and so on WERE actually created by the Sage specifically to be used to fight Juubi. Too bad the alliance managed to lose each and every one.

 

I'd like some backup on this. The Anime shows it as blue almost universally. Only things that alter the nature of Chakra being expellled alter it's color. I.E. The Kyuubi is A Demon, and thus his Chakra is Red. Orochimaru's Curse Seals corrupt the Chakra and so it comes out as a dark purple. Healing Jutsu are the color they are because the Chakra has been shaped and changed and altered in nature.

Normal, base-line Human Chakra is Blue.

Edit: Huh, he's right.

 

As I mentioned, chakra is supposed to be colorless and invisible. The colors you see in the anime and outlines you see in the manga are supposed to be visual shorthand that chakra is being channeled. The different colors are being used to indicate that there is something different/unnatural about that type of chakra. As for the yellow chakra, it was mentioned here.

---------- Post automerged at 10:29 PM ---------- Previous post was at 10:12 PM ----------



This is what chakra is supposed to be like. Not blue. Not yellow. Invisible.

Of course that is my opinion, and most people take the 'colors' of chakra as fact, rather than a visual aid. Which would make the Byakugan's ability to see chakra less than pointless.

 

Hmm, not sure about that.

The Byakugan's chakra-ability was to 'see chakra inside the body' with a high definition. The higher the defintion the stronger the Byakugan. Not just 'see chakra'. The general idea of what I've seen is that Chakra is only visible when used in high amounts, but not used very efficiently. The spend-off can be seen escaping from the body, mostly around where it's being focused.

So, 'leaking Chakra' isn't necessarily a sign of power as it's commonly used in fanon, but more a sign of a lack of control.

Of course, this is my take on it.

Honestly, even if Naruto's chakra was supposed to be Yellow, and the Manga says it was... I prefer Blue, yellow 'power sources' makes me think of DBZ, and that is not a good association.

 

I assumed that the Byakugan and Sharingan can see a wider spectrum, so they see individual chakra 'signatures' due to their unique colours and can see chakra natures, like Kakashi seeing Kakuzu use an earth jutsu and Sasuke seeing that Deidara's bombs are earth-natured. Plus the main thing about the Byakugan is that it sees chakra inside the body i.e. the chakra pathway system so chakra being visible wouldn't reduce its effectiveness. Seeing raw, non-transformed chakra being release wouldn't be a common sight anyway.

Would you say that this, this and this shouldn't be taken as how they actually appear?

I believe so.

Maybe. But it seems to be few people have heard so I could believe no-one else had done it because it isn't well-known and one of the hardest things you could learn to do.

 

Is there some confusion between the Sage's Creation of All Things & similar effects and general Yin-Yang Release? It always came across to me that the Sage's unique insight and ability allowed him to take the standard Yin-Yang Release to the heights of creating life.

 

Well, Tobi first mentions it here and here.

 

Hmm, I may have misunderstood a few things. Will have to revise the theory a bit.

About the sage's bloodline, it seems that Yang Release is dominant in the Senju (going by the only two examples we really have, Tsunade and Hashirama) while Yin Release is dominant in the Uchiha (they seem to create a lot of fleeting forms with the upper end Sharingan abilities, and the Sharingan's standard affinity for Genjutsu).

When it comes to the Sharingan and the Byaakugan... I thought the Sharingan could perceive detail in absolute clarity (I don't think anyone disputes this) and could see the nature of Chakra (the Sasuke/Deidara fight). The Byakugan has the telescoping ability to see to distance, to small scales and through solid matter (none are abilities the Sharingan has).

The Sharingan cannot see more detailt ahn a normal eye could see but the user has total clarity of perception. The Byakugan is actually an enhancement and can be used to see fine structure in the human body. To use an example, the Byakugan would be able to pick up on all features of body language but it would be up to the user to actively look for them, the user of the Sharingan would notice all visible effects instinctively (in both cases, interpretation is another matter).

(I then realised you were talking mostly about the Vhakra seeing affects of the eyes, never mind, ignore as necessary)

 

It's interesting that this thread came into life right now. Why? Because I'm working on something I've called the Naruto Revisioned Project (currently unpublished anywhere online).

What I am attempting to do is come up with a complete picture of the setting that erases any inconsistencies from the manga and fills in vital information that I may need at some point for any story I write. The project includes: chakra theory, jutsu theory, village sizes, village comparative strengths and weaknesses, a revised ranking system for comparing characters, etc. Currently the project is incomplete sitting at about 8000 words on my other laptop. I plan to post it here when I'm finished. By no means do I expect other people to accept anything I write as canon, but I hope that this tool can be useful to others as well.

When I finish this or at least get the first draft completed to my satisfaction I will open a new thread for it since although it will overlap heavily with this topic, it also goes in some different directions.

A few vital points about chakra theory:

1. Chakra is in all things. A common fandom mistake is to treat chakra like mana from western RPG's. I am nowhere near an expert on eastern culture but I studied enough Wikipedia articles to know better.

2. Chakra is composed of physical and spiritual energies. This is made explicit in the manga.

3. Chakra is the fundamental life force in all things. Chakra is a REAL LIFE metaphysical concept (hence why I went looking in Wikipedia).

4. There is no such thing as not having chakra. If you lack chakra, you are dead.

5. There is no such thing as "doing something without chakra." If your heart beats you have used chakra. That's right -- your body is both producing and using chakra every second of every day that you live. The amount you use corresponds to how hard you exert yourself.

6. Your chakra can be disrupted or depleted by an outside source, but it can never be sealed off from you without killing you.

7. Ninjas naturally have stronger chakras than civilians. This is why even young academy students with minimal chakra control can perform feats like jumping 10 ft in the air -- something that real life Olympic athletes cannot do.

8. Different people's chakras have different natural ratios of physical and spiritual energies. It should almost never be 50/50. Why? Because people like Naruto should be heavy on physical energy while people like Sakura should be heavy on spiritual energy.

9. The above naturally affects which techniques are easy or hard for you to learn since different techniques should require different balances of physical and spiritual energy. Most likely, of the academy three, Bunshin requires the most spiritual energy relative to physical energy. This is my explanation for why Naruto cannot perform Bunshin but can perform the much harder Kage Bunshin: he does not have the control (at that time) to manipulate his chakra to have the correct ratio of physical to spritual energy. Most likely Kawarimi was the easiest technique for him to learn.

10. Controlling your chakra is second nature to a well trained ninja. Is there anyone who actually believes that a 100 pound woman (Tsunade -- and her actual canon weight is listed as 107 pounds IIRC) has the raw physical strength to punch through boulders, something real life body builders could never dream of doing? Her body naturally controls its chakra to produce super strength. The best part? It's no more difficult for her to control this strength then it is for you to control yours. In fact its easier because she's trained in using it for her entire life while you're sitting behind your computer postulating about how chakra works in a manga written in a foreign language on the far side of the planet. When she needs that strength, her body controls the chakra on its own.

I cannot think of anything else on the general theory (I'll go into jutsu theory below) at the moment and I'm away from my other laptop. Let me move on to my view of how one should think of chakra (keywords: my view):

I think the normal fandom view is to treat chakra as one big tank which starts at full and then gets depleted as you perform jutsu. This tank slowly fills back up in time. Basically, mana from any western RPG. This viewpoint I disagree with entirely.

As far as I'm concerned, there should be no tanks anywhere in the picture. Your body constantly produces physical energy and spiritual energy. These energies naturally combine to form the chakra running through your body. The more "fresh" you feel, the more physical and spiritual energy your body can produce. Just like real life. If you are exhausted you will not run your best mile time. If you are fresh and relaxed you will do better, assuming all other factors are equal.

Ninjas train to squeeze extra physical and spiritual energies out of their bodies. Even for ninjas (who naturally have large amounts of chakra running through their coils at all times), it is necessary to produce more chakra to perform a technique. You are literally altering nature. That's not easy.

When you do this you are literally forcing chakra out of your body. That's okay because the body learns how to deal with this and becomes more tolerant of this as you improve. However, no matter how you look at it, this is taxing. Imagine sprinting 100 meters as fast as you can while simultaneously trying to solve the hardest puzzle you can imagine under a time limit. That's what it should feel like to gather as much chakra as you possibly can all at once.

Your body needs to relax to recover its energy after doing this. The ability of the body to recover is an essential element to being a good ninja.

In summary, my way of thinking of chakra has become to look at it from three aspects:

1. Control (I'll get to this in a minute)

2. Potency (the amount you are able to expel at any one moment)

3. Recovery (how easily your body regains the ability to force chakra out)

All jounin ninjas should have high ratings in 1 and 2. If we look at someone like Itachi, he should have extremely high potency since he can perform massive terrain changing techniques like Susanoo. A genin could never do that no matter how much they tried, even if they had the Mangekyou Sharingan. They just don't have that kind of power unless their name is Naruto. However, Itachi has low recovery due to his disease. This explains his low stamina rating in the databook.

When we talk chakra capacity, it's really a combination of 2 and 3. Potency is needed to perform a big technique, recovery is needed to do it again.

Performing jutsu:

The general technique for performing a jutsu can be summed up in three steps (this part is mostly supposition on my behalf, but I think you're all smart enough to work that out).

Step 1: Gather chakra. Because the chakra running through your body is not enough to perform a technique, you must squeeze out more.

Step 2: Mold chakra to the correct "frequency." What I mean is that the chakra you use to perform the technique must have not only the correct balance of physical and spiritual energies, but must be oriented to the correct element.

Step 3: Control the flow of chakra as necessary. This could, for instance, involve concentrating chakra to your lungs and throat and then expelling out in the correct manner to produce a fireball.

Most likely, ninjas learn step 3 before step 2. Steps 2 and 3 a ninja will continue training throughout their careers. For example, a ninja will try to unlock the power to use more elements, or may work on controlling the flow better to improve their taijutsu.

How well you can do steps 1, 2 and 3 can be summed up in general as "chakra control." Sakura excels at step 3, while Sasuke may actually be better at step 2. Naruto is probably the best at step 1 by now as he has had to learn not only how to gather his own chakra, but the Kyuubi's.

Fuuinjutsu:

I think my take on fuuinjutsu is not something anyone else uses. For purposes of the Naruto Revision Project I am working on, I have characterized fuuinjutsu as all techniques which involve barriers, binding, containing, or one other thing which I forgot.

Fuuinjutsu is not simply techniques written on paper. This is actually in direct contradiction to the manga: ShikiFuuin, for example, does not involve writing down anything. The symbols appear after using hand seals to summon the Shinigami.

I've characterized how good you are at fuuinjutsu by three categories:

1. Functionality: what can you do with seals?

2. Stability: how well do your seals hold up?

3. Efficiency: how much chakra do you expend to do this?

In my head I use computer programming as a sort of analog. What does your code do? How buggy is it? What kind of memory and processing requirements are we talking about?

Kushina says in the manga that the Uzumaki were great at sealing but their style was a little rough. Unless the translation I've read is just terrible, it's abundantly clear that she's talking about fuuinjutsu when she says their style was a little rough. I've taken this to mean that the Uzumaki were great at functionality and stability, but that their seals were pretty chakra demanding. To put this at a really basic level, it's like using bubble sort (order n squared) in your code instead of a faster (n log n) sorting algorithm. Well, that's maybe over simplifying too far, but I want this explanation to make sense to people who have never worked with a compiler before.

For the record, concerning Hiraishin and other spacetime techniques, my interpretation is that the significance of the seals Minato uses are to provide markers for where he re-enters the spacetime continuum. Tobi does not use seals of any kind. Kamui does not need a marker because Tobi gets taken to that strange room every time he uses it. How he knows where to go from there I have no idea.

I have, however, given Minato the privilege of getting to be the best master of fuuinjutsu techniques ever. That does not mean that he's the best at all aspects of fuuinjutsu, just the best overall.

Genjutsu theory:

I'm still working on this part of the project, but I've divided genjutsu in three different ways:

1. Area genjutsu vs targeted genjutsu: that is, whether your genjutsu affects ALL living things in a specific region of space or whether your genjutsu targets a specific individual.

2. Seal based vs sensory based genjutsu: seal based is formed via hand seal, whereas sensory based works by using one of the targets sensory mechanisms against them (e.g. vision or hearing).

3. Perception altering vs reality altering: perception altering techniques change how you see the world but do not prevent you from moving around (e.g. the Nidaime Mizukage's technique), whereas reality altering techniques pretty much shutdown your body -- you cannot even move, your entire reality has been altered.

So for instance, we can characterize Tsukuyomi as a targeted, sensory based, reality altering genjutsu. Meisagakure no Jutsu (IIRC that's the name for the Nidaime Mizukage's technique) is an area, seal based, perception altering genjutsu.

It's not so much one type of genjutsu being better than the other as it is each type of genjutsu having its own strengths and weaknesses. I would consider both Itachi and the Nidaime Mizukage as candidates for "best genjutsu user in history," yet their techniques are completely different. For Itachi to learn the Nidaime Mizukage's style, he would effectively have to relearn genjutsu.

Dispelling genjutsu is in a sense much easier because there are only a handful of tricks one can use. This is the difficulty for genjutsu users when trying to hone their art: all your work can be broken in an instant. But the payoff is worth it. Genjutsu is very subtle and fast acting. Even if your opponent dispells your technique you can still fall back on whatever ninjutsu and taijutsu you know -- but if they can't, there's a very high chance that they are already dead. Not 100% mind you (see Team 7 + Kabuto vs Ame gennin team in CE arc), but very high.



I hope this helps...

 

All living, sentient things. Everything else has natural energy.

 

That was what I intended to say when I wrote that, but when you pointed it out I got curious. In fact, neither interpretation can be definitively accepted as truth. So even though I don't disagree with your view, I'm going to play Devil's Advocate for a moment and explain why it might not be true.

Chakra is an essential concept both in Hinduism and Buddhism, but Kishimoto seems to borrow his notions of chakra more from New Age medicine:
http://en.wikipedia.org/wiki/Chakra#New_Age

Moreover, chakras are really supposed to be loci of life energy, rather than the life energy itself. So the chakra from the anime/manga really should be called ki:
http://en.wikipedia.org/wiki/Qi#Philosophical_roots

("Ki" is the Japanese name for "Qi")

My guess is that he did not do this because he wanted to separate chakra from DBZ ki to avoid confusion, although I may be entirely wrong in that regard -- I'm no expert on eastern culture/mythology and I'm basically just making not-really-educated guesses based on articles I've read off the internet.

Anyway, the key point in all of this is that depending on your interpretations of ki and chakras, the idea of "chakra is in all things" may actually be very literally true.

Alternatively you could say that "pure nature energy is itself a form of chakra," as are "pure physical energy" and "pure spiritual energy." When ninjas say that chakra is a "combination of physical and spiritual energy," this is because the human body produces both physical and spiritual energy. In other words, the chakra you naturally produces is comprised of both. For different people the balance should be different and hypothetically it should be possible to completely separate them into different chakras.

In fact, you could say that "yang release" might be "pure physical energy chakra" and "yin release" might be "pure spiritual energy chakra." Ergo, chakra is in all things.

 

You've all forgotten that all the really cool ninja call it "Catra"

 

To me, whatever's explained in the manga would trump the explanation given to the real life concept.

In which case, I'd say calling pure physical/spiritual energy a form of chakra a contradiction of the canon definition. They're different forms of energy, yeah, but chakra is always the mixture of two or more types of energy. So yin/yang chakra can't be pure spiritual/physical energy 'cause then it wouldn't be chakra at all.

Plus physical energy comes from the cells and spiritual energy comes from the mind so it wouldn't make sense for it to exist in anything other than living, sentient creatures. The only possible exception that comes to mind are plants since they're living organisms but they're probably limited to physical energy, if even that.

 

It does not contradict the canon explanation. The manga never specifies that the mixture of physical and spiritual energies must include nonzero amounts of both. When the concept of physical and spiritual energies was introduced it was in the context of Team 7 learning how to use chakra to climb trees. None of them would have had the skill to separate their physical and spiritual energies anyway, and that's even assuming an academy student would know that such a thing is possible.

You're taking the wording too much for granted by assuming that the word "mixture" means that there absolutely mustbe nonzero amounts of both. That does not follow. First, it's a translation into english so you need to be careful not to over parse the words. Second, the word mixture does not by definition mean "two or more are nonzero" unless you are explicitly referring to a chemical mixture, which is where two or more different non-chemically bonded substances that are mixed in no fixed proportion to each other. According to your own definition, chakra is only formed when physical and spiritual energies bond ergo that definition of a mixture does not apply.

I'm not saying the idea I threw out on the table is the right one, but you should not automatically dismiss it since it is canon compliant.

Also, a thought that just occurred to me: if chakra is only formed when physical and spiritual energies bond, then it should form in a fixed proportion of physical and spiritual energy, which without further knowledge one should assume is the same for everyone -- which is not canon compliant because everyone's chakra is a little different as we saw when Naruto started handing out Kyuubi chakra to everyone. Further, what is meant by the Yondaime sealing away the Kyuubi's yin chakra into himself and the yang chakra into Naruto? If chakra is only physical and spiritual energy, it logically follows that yin is spiritual energy and yang is physical energy because there is no other way to divide it since neither of these involve the third component of natural energy. There's no other logical choice. But then "yin chakra" is referring to spiritual energy, which you insist is not chakra.

The more I think about it the more I think you're wrong about how chakra is formed. I don't necessarily disagree with the notion that chakra is only in living things, but I do disagree with the notion that chakra is only formed.

 

I’m not seeing it. I’m not gonna get all science-y about it but by all accounts*, chakra is formed from two kinds of energy being joined together. Whether you call it a mixture, combination, blending or whatever else is up to you but the sentiment’s the same; more than one ‘substance’ being brought together to form a whole.

*Kakashi (or Exposition!Sakura), Jiraiya, Fukasaku and the first databook all say it in one way or another.

When someone say yang chakra or yin chakra, then I think of chakra that has significantly more physical energy than spiritual energy or vice versa. Which we already know it treated as a special kind of chakra ever since Shikamaru’s fight with Tayuya. So it’s based on one type of energy, which is why they make references to it or yin/yang, but I wouldn’t think of it as that energy alone since it doesn’t really fit with everything else we know about chakra. And I wouldn’t say that normal chakra has that ratio in equal amounts either but it still involves both (a mistake I made when I initially thought up the Yin-Yang theory/rule).

I’d hesitate to use the Bijuu as an example at the best of times since they’re obviously running on a different set of rules i.e. they originated from the Juubi, are composed entirely of chakra and were created by the Sage’s abilities. But I have heard what I think is a solid theory on the subject (even if it uses some real-life symbolism which I admitted I’m not a fan of):

 

But the elephant in the room is: just what the hell are physical and spiritual energies? You cannot say "I wouldn’t think of it as that energy alone since it doesn’t really fit with everything else we know about chakra" without knowing what physical and spiritual energies are.

My best guess would be that physical energy is needed for a jutsu to have any physical effect in the real world, while spiritual energy is needed to direct it. Maintaining the shape of the bijuudama would be impossible without yin energy.

The only issue you've brought up that there is a need to address is the Kyuubi seal, but asking why Minato did what he did, how he did it, etc, raises lots of questions that no theory explains at all. It may be that bijuu just work differently than humans and all normal laws go out the window. They are just gigantic masses of sentient chakra that assume physical form, right? When you get down to it, that doesn't make sense in the context of "normal rules." Even if you say the Kyuubi is still left with some yin energy but no yin chakra, as long as he has yin energy he should be able to produce yin chakra. If you have any spiritual energy at all it is possible to make yin chakra. No theory prevents that from being the case.

One possibility is that not all the yin chakra was sealed, just the vast majority of it, say 99% of Kyuubi's spiritual energy. Another possibility is that since the Kyuubi is just a giant mass of chakra, its physical and spiritual energies actually have sentience of their own. That doesn't really mesh well because if a physical energy has sentience then it also should have a spiritual energy, should it not? Yet another possibility is that it has to do with the seal: Minato did to Kyuubi's spiritual energy the same thing that Naruto did with Kyuubi's remaining chakra.

This last theory would make this particular page of the manga make more sense to me (this chapter is very recent so.... SPOILERS):
http://www.mangahere.com/manga/naruto/v63/c631/10.html

Spoiler

The Kyuubi reacts even before any physical signs of Minato using Kyuubi chakra. Basically, the theory would be that Kyuubi's yin energy has just been put out of his reach and when Minato uses it, Kyuubi starts draining Minato's energy -- this is how he knows Minato is entering KCM.

 

I'm the guy that came up with that theory Knight posted, so I'll throw my two cents in on this discussion.

What the hell are physical and spiritual energies? I had a post on TFF about that, so I'll quote it here:

So spiritual energy is basically psionics or psychic powers, which is why stuff like genjutsu and the Yamanaka's mind/body switch, mind reading and telepathy jutsu would be classified as yin release. Physical energy, on the other hand, is produced by living tissue and controlling it let's you manipulate living tissue, which is why stuff like Mokuton, medical jutsu and the Akimichi's body expansion jutsu would be classified as yang release.

Mixing those two energies together gives you a new substance that is more versatile than the parts that make it up, letting ninja manipulate the world in ways that neither physical energy or spiritual energy alone could accomplish. Presumably there were healers and mind-readers and illusionists before the Sage, but his discovery of chakra and invention of ninjutsu allowed for the creation of new kinds of jutsu like elemental jutsu and time-space jutsu.

That's my theory anyway.

As for why Kurama is sentient despite supposedly not having any yin chakra, it could be because he only mostly lost his yin as I theorized earlier. Another possibility I just came up with: Perhaps while his yin is sealed away, it's impossible to truly separate a bijuu's spiritual and physical energy and thus he can still access it in some reduced capacity, allowing him to think and form bijuu-damas. It could be sort of like how the Kyuubi can still give his chakra to Naruto's clones and take chakra away from them despite the distance separating them. Time-space fuinjutsu seals are weird like that.