Hollow Combat

**Kūdō** (空道, Hollow Way), also known as **Matanza** (Slaughter) is a "style" of fighting or more precisely a group of techniques used by Arrancar primarily but which can be replicated by lesser hollows.

## ***Overview***

**Kūdō** is a family of techniques developed by hollows and arrancar alike to make use of their hollow physical and spiritual physiology to better survive in a fight when their innate hollow ability is insufficient or outright countered or negated by the enemy's own abilities. While it may appear like a kind of martial art there are very little teachers of Kūdō and most hollows who know the techniques only do so by imitation or by getting an innate instinctual sense for it.

The fundamental principles behind Kūdō are that:

* Hollow reiryoku is innately super-compressible and thus can be compressed much more than the reiryoku of other entities.
* An hollow's reiatsu vents are located in every pore of their body and are the same system through which a hollow breathes. Because hollows lack a heart to pump blood most hollows must breathe through their skin.
* Hollows lack a kido organ, this organ instead is the garganta organ which allows Hollows to warp space and time to generate their various portalling abilities.
* The musculature system of a hollow are much more powerful than that of a plus because it reacts to reiryoku much more more than an untrained plus'. The difference in power drops as pluses train their bodies and muscles however.
* Hollows innately have high-speed regeneration and this regeneration can be sacrificed by some unknown mechanism for greater power. The leading theory is that all hollow cells are capable of differentiating to other cells but they can be made to be hyper-specialized and thus even "stronger" at the cost of losing their ability to become other cells as easily.

## ***Techniques***

### *Cero*

The **Cero** (虚閃 (セロ), Sero; Spanish for "Zero", Japanese for "Hollow Flash") is a basic technique employed by menos and arrancar it makes use of the kumon organ to teleport a bit of the hollow's reiryoku from inside their body to the outside, compress it and "burn" it to release the compressed energy as a beam of light and reiatsu.

Because this technique is quite simple many variations exist and a supermajority of them are performed by Arrancar who now possessing a kido organ are capable of shaping the compressed reiryoku before it is "burnt" to enact a kido transformation into the cero to make it more useful and/or powerful.

#### **Cero Variations**

The following variations of cero are not exclusive to anyone and theoretically can be learned and used by any hollow:

**Gran Rey Cero** (王虚の閃光 (グラン・レイ・セロ), guran rei sero; Spanish for "Grand King Zero", Japanese for "Royal Hollow Flash") is the simplest variation of the Cero and it consists in nothing more than adding hollow blood to the ball of compressed reiryoku before it is discharged. The blood of an hollow possesses supernatural chemical properties which can empower the resulting release of power tremendously. The quantity of blood is not as important as much as its presence within the core of the compressed ball.
**Cero Oscuras** (黒虚閃 (セロ・オスキュラス), sero osukyurasu; Spanish for "Dark Zero", Japanese for "Black Hollow Flash") a tremendously powerful variation of the cero which can be used by any hollow theoretically but most never actually figure it out. It consists in taking the compression of the reiryoku to such a level that the energy occupies a volume below its Schwarzschild radius collapsing the ball into a reiryoku black hole. At this point there can be no more compression and the reiryoku even when "burnt" cannot escape the ball so the Garganta Organ is used to release the reiatsu as a beam of pure destruction
### *Bala*

The **Bala** (虚弾 (バラ), Bara; Spanish for "Bullet", Japanese for "Hollow Bullet") is a more advanced technique employed by arrancar, it makes use of the kumon organ to teleport the reiatsu generated by "burning" hollow reiryoku from inside the body as its burnt and then "shooting" it with a movement of a weapon or a body part.

The bala is many times faster than a cero despite being essentially the same because it skips the compression stage entirely and remains thus weaker. This technique is different from simply releasing reiatsu through the skin because doing so leads to nothing special due to most of the power of the reiatsu being lost as it travels to the vent.

### *Hierro*

The **Hierro** (鋼皮 (イエロ), Iero; Spanish for "Iron", Japanese for "Steel Skin") is a hollow technique that quite simply consists in the hyper-compression of a majority of the reiryoku within a hollow's body. A hollow's reiryoku when compressed in this manner will interact with the hollow's physiology in a bizarre way and make the hollow incredibly sturdy and yet just as flexible granting them what is essentially a virtual increase in density without the change of mass.

The strength of any given hollow's Hierro is directly proportional to both the amount of reiryoku a hollow possesses but also the quality of the hyper-compression with hollows of lesser energy levels to manifest an overall greater level of hardness from simply being able to compress further than more powerful hollows.

### *Sonído*

The **Sonído** (響転 (ソニード), Sonīdo; Spanish for "Sound", Japanese for "Sound Ceremony") is a technique discovered by accident after the discovery of **Hierro** and it consists in simply venting the reiatsu generated by the hyper-compressed reiryoku or its burning. Because of the hyper-compression of the reiryoku the resulting reiatsu released will possess tremendous kinetic energy as such when a hollow vents out this reiatsu they will experience an acceleration on their body similar to having a rocket attached to that area of the body.

Because **Sonído** functions basically like turning on a thousand rockets on the hollow's skin it is impossible not to produce a sound, it can however be used for combat much more easily than other mobility techniques and can even be combined with them due to working by different methods all together.

Hollows which are masters of sonido and the use of the garganta organ can generate what is essentially an **bala** that is as powerful as a **cero** by using the mechanism of the sonído to generate an hyper-compressed release of reiatsu and teleporting this reiatsu out the body instead of releasing it through the pores as normal sonido would dictate.

### *Pesquisa*

**Pesquisa** (探査回路 (ペスキサ), Pesukisa; Spanish for "Inquiry", Japanese for "Probe Circuit") is a technique employed by hollows which consist in the hyper-decompression of part of their reiryoku and then "burning" it to generate an harmless type of hollow reiatsu which mixes with the light of an environment readily and can convey information to an hollow of the reiatsu of other people in a large area by the interference it causes in the radar like dispersal of hyper decompressed reiatsu.

#### **Pesquisa Variations**

**Pesquisa Pequeña** (Spanish for "Small Inquiry") is a technique developed by Kuniyuki and understood by Tomo it consists of generating the pesquisa light and manipulating it into a tiny sphere that can be placed on a surface to spy on someone, because of its design it is able to convey audio information by vibrating to any sound generated in its vicinity.