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This article, Seiatsu, is property of Ten Tailed Fox

"W-what?! One second it's normal and then it suddenly spikes tremendously!"
Kento Tensei commenting on Koga's "odd" reiatsu

Seiatsu (制圧, Oppression) was originally thought to be a type of Shinigami who's emotions have been animated by the Hōgyoku; During their later confrontation in Koga's Inner World, Dark Koga explains to Koga what a Seiatsu really is. A Seiatsu is a being that, through the powers of the Hōgyoku, is able to cross the threshold and stand at the crossroads of many spiritual races, essentially becoming something else entirely. He goes on to say that Shinigami, Hollows, Sōzōshin, and their crossbreeds exist in a world dominated by mental and physical limits, as well as the things of the spiritual. He then says that a Seiatsu has stepped outside this realm. . There is only one known case in the form of Koga Tensei. They are Shinigami who have gained unique power due to this, unlike that of Vizard or Arrancar. Dark Koga goes into the concept more by stating that Hōgyoku actually gave life to Koga's desires by transferring it's powers into him, which made him a Seiatsu.

It should be noted that this transformation greatly resembles Sōsuke Aizen's transformation during the Fake Karakura Town arc, meaning that the two could be related somehow.


"...there is one that knows your powers intimately. The Hōgyoku, which gave me life. You may control interactions, but the power of the Hōgyoku is outside the mental, physical, and spiritual. It's power is far beyond that which has ever been seen in Soul Society. You may think you know this, having once been bonded with it, but there is one thing you didn't know about it's power and that your dear friend Sora had begun to suspect; If the Hōgyoku's power is Desire Materialization, then what happens when you give life to that beings desire? Actual life? I think he's back at Las Noches learning what some of the effects are now. The Hōgyoku was drained of it's powers. They reside in me. Once the boy learns to control me...well that I'll leave for you to find out."
Dark Koga to Seireitou Kawahiru

Seiatsu are extremely rare. In fact, it is completely impossible to become one through natural means. It is even impossible to reproduce them via inventions, reiatsu experiments, or even specialized machines. The only known Seiatsu to have ever existed is Koga Tensei.

During a Seijin exploratory mission to Hueco Mundo and after a brutal confrontation with Takashi Sora, Koga's team came under the attack of the Arrancar, Xerxes Averian. In the midst of the attack, Koga's friends arrived to assist him and ends up getting dragged into the attack. Koga's reiatsu begins to fluctuate and, after Seireitou's unconscious form is also attacked, he begins to transform into a Seiatsu. Sora later comments that he had the Hōgyoku on his person during his confrontation with Koga's group, and forced it to obey Koga's desires, unknown to Koga himself. Since Koga was desiring to free Seireitou from his Hollow form at the time this was happening, the Hōgyoku began to act on it until the object found something interesting. It somehow realized that Koga's true desires were to protect all of his friends from harm, because his friends were ever so few. The Hōgyoku also realized that Koga could not do this without another source of power, so it lumped all of his negative emotions together to create an inner being called a Dark Side (暗部, anbu) or more specifically Dark Koga.

Originally, the transformation that resulted from Dark Koga taking over Koga was thought to be Hollowfication, however, Renge Yamato comments that the reiatsu that is produced feels nothing like that of a hollow's. Later, Sora also comments on this. He states that, for some reason, the Hōgyoku used traits from Seireitou's Hollowfied form (which Koga was watching while the Hōgyoku was unknowingly transforming him) in the transformation it was creating; such as a change of hair, hollow eyes, and dual voices.

This process had extremely negative effects on the Hōgyoku; something that was not planned for by Sora and shocked him once he found out. In order to give Dark Koga the power source the Hōgyoku was initially trying to produce, the Hōgyoku transfered it's odd, yet truly immense energy into Dark Koga, forcing the Hōgyoku back into it's dormant state.


During their later confrontation in Koga's Inner World, Dark Koga explains to Koga what a Seiatsu really is. A Seiatsu is a being that, through the powers of the Hōgyoku, is able to cross the threshold and stand at the crossroads of many spiritual races, essentially becoming something else entirely. He goes on to say that Shinigami, Hollows, Sōzōshin, and their crossbreeds exist in a world dominated by mental and physical limits, as well as the things of the spiritual. He then says that a Seiatsu has stepped outside this realm.

The reason for this, is stated in the words of Tessai Tsukabishi, who said the Hōgyoku's power "is unlike anything ever seen in Soul Society, completely unrelated to reiryoku. It has a presence that feels as if it's trying to stifle my very existance!" Since this power got transfered into Koga, his spiritual energy has now gained these properties. Dark Koga in particular becomes confident enough to fight Seireitou Kawahiru, who had released his Bankai, without even drawing his sword.[1]

Shinigami and Seiatsu differ in some ways;

  • Zanpakutō: During Dark Koga's fight with Seireitou, while Koga's body underwent the Seiatsu transformation, Koga's Ryūjin Koji burst into billions of dust-sized particles and then reformed. Dark Koga explains that this "Seiatsu zanpakutō" functions like a typical Shinigami Zanpakutō; with a Shikai and Bankai, however, there is one difference. Dark Koga says that a Shinigami's zanpakutō is a manifestation of it's owner's soul. But the Zanpakutō that is formed from the Seiatsu transformation, being of the Hōgyoku's origin, is a manifestation of it's owner's desires.
  • Hōgyoku Energy: After fully transforming, Koga ceased to be a Shinigami or Human, instead he was now completely a Seiatsu. His spiritual energy was then completely replaced with that of the Hōgyoku's energy and became quite overbearing to his friends and family, who were Shinigami and Quincy.

Powers & Abilities[]

Like Shinigami, Seiatsu have a multitude of combat skills and abilities, some of which are similar to those of the former, and some of which are variations on ordinary Shinigami powers. Since the power is derived from the Hōgyoku, a Seiatsu can also preform Hollow powers and other abilities from other spiritual races.

  • Kyūkaīn no Shikyo (九改印死去, Nine Changing Seals of Death): A Seiatsu technique that creates nine energy rings that circle a foe's technique and seals it. This works by having the open parts of the rings act like vacuums, which when in position, will suck up the techniques in question and seal them.
  • Senkō (閃光, Flash or Glint): Senkō is the Seiatsu movement technique. Being at the crossroads of all spiritual races, a Seiatsu's Senkō is faster than such techniques as Flash Steps or Sonido. When using Senkō, movement is so fast that it causes the user's energy signature to vanish completely until they reappear, making it a formidable technique. Koga likens the technique to teleportation, as the movement itself is almost impossible to read and the user could turn up anywhere after its use.
  • Bōei (防衛, Protection) is a technique on a similar scale to an Arrancar's Hierro. Koga's dense reiatsu is condensed around his body to the point where ordinary attacks become useless against him. Strong enough opponents can pierce this defense, however, it makes him increasingly difficult to cut, as he can catch even a released Zanpakutō barehanded.
  • Cero (虚閃 (セロ), sero; Spanish for "Zero," Japanese for "Hollow Flash"): Being at the crossroads of all spiritual races, Koga has access to the Hollow, Arrancar, or Vizard attack; the Cero. Cero are high-powered energy blasts that can be fired from various body parts, such as mouth, tongue, hand or fingers. Just like Arrancar, Koga seems to be able to make his own variants of the Cero attack.
  • Kaiganseki (開眼, Spiritual Awakening Gate): This gate is similar to the Senkaimon used by Shinigami to get to and from both Soul Society and the Living World, with one upgrade; it can also allow him to travel to Hueco Mundo. To access it, a spiral seal will appear on his hand, with a similar seal appearing in energy form in the air in front of him. He will then touch his seal to the seal in the air and twist it, opening a large hole in the dimensions. If he is traveling to Soul Society or the Human World, he has to cross the Dangai Precipice World to reach his destination. If he is traveling to Hueco Mundo, it will create a similar effect to a Garganta.


  • Tenkai (天解, Heavenly Release): Koga's Tenkai is a release of his Zanpakutō as a result of his Seiatsu transformation. In many ways the release is similar to an Arrancar's Resurrección in that it changes Koga's physical appearance greatly. The release is a sign of Koga's mastery of the Hōgyoku's power and is a release on par to Bankai.


While still transforming into a Seiatsu, Koga took on many forms; all under the control of Dark Koga;

Hollow-like Transformation: The first signs of a transformation is Koga's eyes turning into that of a Hollow's, black pupils, yellow irises and black sclera, as well as his hair turning dark grey and lengthening slightly. In this form, a white substance erupts from his zanpakutō-strap holding clip on his chest. It slowly consumes his body as it slowly begins to form the appearance of his next form (see below). The first time he used this form, he was under the control of Dark Koga. Everytime he has used it since, he has been in some degree of control.

  • Enhanced Speed: Koga manages to move at exceedingly incredible speeds, quick enough to appear behind the likes of his Master, Junsui Kirei's back and effectively counter him before the former could even turn to face him.
  • Enhanced Stamina: He can effectively continue fighting for several hours in advance, showing no sign of tiring or injury to himself.
  • Enhanced Strength: His strength has now increased to the point, where he can pick up and even throw the gigantic form of Zacarias Donato's released form with little to no effort.
  • Enhanced Durability: Koga's durability has greatly increased, able to withstand several large explosions in his battle with Xerxes Averian at close range with no visible damage. His skin and hands are also strong enough to catch and hold onto Xerxes's strongest attack. He has also shown himself capable of withstanding incredibly brutal beating from foes without showing signs of pain or even care.
  • Enhanced Spiritual Power: Since the Hōgyoku transfered it's unique energy into Koga as the transformation's main power source, Koga now has dual-type spiritual energy which is half Shinigami, half Hōgyoku. Like the Hōgyoku energy, Koga's spiritual power becomes overbearing, unlike anything else in Soul Society, and completely unrelated to reiatsu. His energy increases as his transformation progresses. By the completion of his transformation, his spiritual energy has reached a whole new level. Renge comments that it is the largest amount of spiritual energy he has ever seen in one body.
  • Enhanced Telekinesis: His Seiatsu powers even effect his Shiro Nagare manipulation of his Seijin powers. Of all his new powers, this one is the only one that will remain outside of his transformations. His telekinesis is now deeply linked to his emotions. During flashbacks that prove emotionally painful for him, the outside world is noticeably affected by earth tremors and the cracking and smashing of nearby objects, all caused by telekinesis.
  • Sara (皿, Disc): This technique, named by Dark Koga, creates an energy disk about the size of Koga's palm. The disk can then be fired, slicing through anything it comes into contact with. Koga has also shown the ability to cause the technique to expand in mid flight to allow it to cover a much larger radius.
  • Regeneration Powers: The cloaked form of the transformation has been demonstrated to actively protect Koga by healing his injuries almost instantly.

The full transformation of Koga's Seiatsu transformation.

Full-Body Transformation: As the transformation progresses, a white liquid erupts from the buckle on his zanpakutō strap and covers his body, hardening in the process. In this new form, he appears as a phantom-like figure. His face is covered with a mask also covers most of his head, neck and throat with the exception of small hole in the back for his now long, crimson hair. It has a plain smooth white surface with the only feature being a bilateral line down the middle, separating the mask into two portions. Koga's outfit also changes: he loses his apprentice outfit and his haori and gains a chest plate and a pair of small slim shoulder guards with designs similar to the mask. He also now wears clothing similar to the Arrancar, with a long-sleeve white coat, white hakama, long white gloves with silver bands all along the gloves. In this new form, he is usually seen carrying his Zanpakutō in his hand, but has also been seen with it suspended from a string-like attachment on the side of his clothes. It should also be noted that when he is attacked, his body appears to crack and fold under damage, only bleeding when an attack is powerful enough. This form is eerily similar to Sōsuke Aizen's transformation during the Winter War, only it seems to take place backwards, with the hollow-eyed Human stage coming before the so called "chrysalis form".

  • Desire Materialization: According to Sōsuke Aizen and Dark Koga, the Hōgyoku possesses a will of its own. Though initially thought to solely possess the power to control the boundary of the two contravening existences, that of Shinigami and Hollow, this was proven incorrect, as the Hōgyoku's "true power" is the ability to capture and materialize the hearts of everything that exists around it. Dark Koga says that this power was given to Koga when the Hōgyoku transfered all of it's power into him. This may explain why Koga has been given some Hollow powers in his Seiatsu form despite not being a Hollowfication; he simply desired to possess them. He has not expressed complete control over this just yet, so it's drawbacks are not yet clear.
Power Augmentation: While within this form, the Hōgyoku's powers supplement Koga's Shinigami powers, giving him a vast increase in both strength and speed. The explanation for this is that the Hōgyoku's energy is overbearing, unlike anything else in Soul Society, and completely unrelated to reiatsu and this power is added onto Koga's already tremendous reiatsu.
Argumented Zanpakutō Powers: When Koga is in his full-body Seiatsu transformation, the power, speed, blast area, force, and size of all of his Shikai and Bankai techniques become drastically augmented to the point of seriously harming a foe. When used with his Bankai and transformation in combination, his Shittonohonō is stated to be his truly ultimate attack. Koga's new tremendous speed allows him to move faster than any of his attacks themselves, allowing him to fire multiple attacks from different directions.
Enhanced Spiritual Power: While in his Seiatsu transformation, the spiritual power Koga possesses becomes even greater than before. During Koga, Kento, Tenyo, and Renge's fight with Xerxes, Tenyo who is Koga's brother, notes that the volume, concentration, and catastrophic nature of his reiatsu didn't seem like that of Koga anymore but more like he was feeling a power even more massive than that of the Hōgyoku's. It has been noted multiple times that when in his full body transformation, his spiritual energy changes into something similar to that of a Hollow despite the transformation not being Hollowfication.
Enhanced Strength: While using the Seiatsu final transformation, Koga gains a substantial increase in strength. As in his fight with Seireitou while possessed by Dark Koga, he was able to block the destructive force of the Kawahiru's strongest Cero, the Cero Lamparos fired by Seireitou. As evident after he unleashed this powerful new state in his battle with Xerxes, and was even able to slightly break his sword with a single slash. He is able to effortlessly block a Cero fired by Zacarias Donato.
Enhanced Speed: While in his full-body transformation, Koga's already formidable speed is greatly enhanced. During his battle for Masterhood in the Order against Renge, Koga’s speed was great enough to completely overwhelm the Master, who was unable to follow Koga’s movements and was forced completely on the defensive from his barrage of attacks. His attacks also become so fast that the opponent cannot even perceive them until after they are hit. He also becomes fast enough to outrun his own Zanpakutō's attacks, allowing him to strike and enhance them or launch simultaneous attacks at the opponent from different angles.
Enhanced Durability: His durability is even more evident throughout the fight as he is thrown through various buildings and obstructions.
Hollow-like Powers: Despite his Seiatsu transformation being something else entirely, he has shown the ability to use some Hollow powers. The reason for this may be because the Hōgyoku has given Hollow powers in the past.
  • High-Speed Regeneration: Like some Gillian-level Menos Hollows, this form shows the ability to instantly regenerate any wound and even a missing limb.
  • Cero: His Cero is midnight purple in color. While a standard ability for Arrancar, Koga's abilities with it are very unique. As noted by Seireitou Kawahiru, like Starrk and unlike most Hollows and Arrancar, he can apparently fire a Cero without a "fighting pose", meaning he can fire it without any warning from body gestures and requires no focus or charging time on the energy, allowing him to fire it instantaneously. He is also capable of firing the blast from his various points on his body, including his hand or chest.


A Demi-Seiatsu is a being such as Sōsuke Aizen or Seireitou Kawahiru who fused/bonded with the Hōgyoku and gained Seiatsu-like powers. The difference between a Demi-Seiatsu and an actual Seiatsu is that once the Hōgyoku was removed from Aizen and Seireitou's bodies respectively, they were immediately drained of any powers they gained while infused with the Hōgyoku, while Koga, who became the vessel of the Hōgyoku's very essence, will keep that power forever.

Behind the Scenes[]

This race has it's basis in many places. After seeing Aizen's transformation in the manga, I decided to delve into it further by making something eerily similar to it, yet not the same thing. It is loosely based on the Jinchūriki theme of Naruto, and even finds some of it's roots in Hollowfication. Keeping true to the Star Wars theme of the Seijin (which Koga is one of), the "inner being" created by this transformation is called a Dark Side.

Note: This page is only for my use. No one, I repeat, No one is allowed to use this idea or turn there characters into a Seiatsu by any means.