Kōga Kuchiki

is a Shinigami introduced in the anime-exclusive Zanpakutō Unknown Tales arc. He is a former 3rd Seat of the 6th Division who later revolted against the Seireitei. He was also a member of the Kuchiki noble family, having married into it.

Appearance
Kōga has piercing olive green eyes and shoulder length black hair and a long ponytail of red hair, with a short tufts of red hair on the left side of his head, and bangs that hung on the right side of his face to frame it. When he was a member of the Gotei 13 he wore a standard Shinigami Shihakushō, along with a long red scarf and a light lavender obi sash, with a beaded-necklace with a pendent. He also wore an intricate white headpiece called kenseikan on the left side of his head to symbolize his nobility that held his ponytail in place with red tufts of hair sticking out (which he later cut off to relinquish his status as a Kuchiki).

While originally his appearance was youthful and fit, after several hundred years sealed away, his physical form has been reduced to a withered-old version of his former self.

Personality
Kōga is a man with a true sense of duty and a commitment to making his family proud. He always tried to remain humble and serious to situations at hand. On the inside however, Kōga was a man who deeply desired to be acknowledged for his abilities and hard work. After being betrayed and realizing that his life as he knew it was gone forever, he had a mental-breakdown, causing him to become consumed by his anger and desire to stand in greatness, leading him to become immensely arrogant in his power to the point of viewing all others as worthless, even his own Zanpakutō, Muramasa.

History
Several hundred years before the current time, Kōga was welcomed into the Kuchiki family as the son-in-law of the Ginrei Kuchiki. He soon gained much respect throughout Soul Society. He in his capacity as the 3rd Seat of the 6th Division participated in a battle between the loyalist and rebel factions of Soul Society winning a decisive victory for the loyalist side single-handedly. For his role Kōga was given much praise and accolades for Captain-Commander Yamamoto himself. Ginrei grew increasingly concerned about Kōga's overconfidence in his powers and made a point to address that he needed to to control himself. Kōga took this in stride but never could understand why Ginrei never acknowledged any of his achievements. He would increasingly speak to his Zanpakutō, Muramasa about this only increasing his overconfidence. As he engaged in battle after battle winning each one with ease, for his efforts he is given a special position by the Captain-Commander, making him the captain of a special force directly under his authority that is totally dedicated to wiping out the remaining rebels. When it became clear that he may very well be the key to winning the war, the enemies, which included three elites, came up with a plan to frame him as a traitor. They achieved this by having their own men attack Kōga knowing he would easily dispatch them and then charging him with the murder and having him arrested. Ginrei arrived to see what happened but upon one of the fallen soldiers admission that Kōga sacrificed them for his own battle lust, he had no choose but allow the arrest until he can determine a way to clear him. Ginrei vistis him in jail and details that his punishment has been handed down. He is for the next few hundred years to be suspended from his seat in the 6th Division and it was determined that his Zanpakutō was a threat to the peace, therefore its powers would be nullified. Ginrei noted to him that he didn't believe any of it but that the top brass has a problem with his Zanpakutō and its ability. He further explained that they weren't afraid of him but Muramasa getting out of control. He then left him their to learn patience as he went to rectify the situation. He was later freed by Muramasa who inspired him to take control of his life again.

That night Kōga killed the elites who framed him. Upon hearing of this Ginrei finds him in the outskirts of Soul Society and confronts him about his actions. Kōga explained that he killed them for their betrayal and that deep down he had hoped that they would have felt remorse for their actions against him, but he found them laughing. He noted that even after killing them he was still filled with so much anger for what they had done to him and the humiliation he had endured. Ginrei remarked that any chance at proving his innocence is gone and that his rashness now put him in a worse position and he will probably be executed. Kōga upon hearing this suffers a breakdown and accuses Ginrei of being like all the others and being jealous of him. Kōga decides to stage a personal revolt against Soul Society and all his enemies. As he killed more people his instability grew. While Muramasa notices that his heart has become turbulent tried to tell him to forget the past and focus on the future, Kōga was obsessed with the idea that everyone hated him and he didn't understand why. While fighting against a group a Shinigami he attempted to release Muramasa and found there was no response, he tried again and Muramasa appeared. While he sat alone in a cave Muramasa appeared as asked him why he would kill innocent bystanders and Kōga remarked that he was teaching Soul Society a lesson for exiling him from their world. Soon he was even abusing Muramasa when he was anything less than absolutely obedient. This disharmony between them gradually caused Kōga to lose his ability to communicate with and even access Muramasa's power. Eventually Genryūsai Shigekuni Yamamoto and Ginrei Kuchiki confronted Kōga and after an exchange of words they realized that they couldn't get through to him. They engage in a minor battle and Kōga went to release Muramasa with no results the two captains take advantage and move to seal Kōga away when they realized he lost total access to Muramasa's power.

Kōga's revolt was never recorded in the Soul Society's history.

Zanpakutō Unknown Tales arc (anime only)
Note: Events occurring in this arc are only in the anime and do not constitute canon material.

Kōga was sealed away, but his Zanpakutō Muramasa eventually resurfaces and begins to initiate a Zanpakutō Rebellion. When Ichigo Kurosaki encounters Muramasa, he states that he already killed his master. However, after Muramasa gains control over Ryūjin Jakka, Genryūsai Shigekuni Yamamoto reveals that Muramasa is planning to break Kōga's seal. He also states that Muramasa is heading to Karakura Town, where Kōga was sealed.

Muramasa eventually arrives at the location where Kōga was sealed, but comes into conflict with Orihime Inoue, Uryū Ishida, Yasutora Sado, and Rukia Kuchiki. He ultimately succeeds in breaking Kōga's seal. As Ichigo arrives to stop him, Kōga begins to awaken. Though Muramasa is ecstatic that his master is finally free, Kōga immediately stabs him in anger, leaving a shocked Muramasa to ask him why. Believing that Muramasa abandoned him before being sealed, Kōga decides to reinforce his status as master by making Muramasa pay with his life. However, Byakuya appears, stopping Kōga's strike and scolding him.

Kōga notices that Byakuya is wearing the ginpaku kazahana no uzuginu scarf and the kenseikan and asks him if he is a member of the Kuchiki family to which Byakuya tells him his name and notes that he is the 28th Head of the Kuchiki family. Kōga then questions if Ginrei finally died but Byakuya scolds him for even saying the name. As he had no right to speak it after he soiled the Kuchiki families name. Byakuya reveals that he pretended to betray Soul Society so he could put the shame of Kōga to rest. After learning that Byakuya is the current head of the Kuchiki clan, Kōga becomes determined to destroy his association with the Kuchiki clan by killing its leader. Muramasa, despite being attacked by his master, insisted that Kōga use his power. Kōga arrogantly instead destroys the remainder of his sword, casting Muramasa away completely. Kōga retrieves one of the blades that sealed him and engages Byakuya, fighting him on even grounds. Kōga turns the battle to his favor by using his illusionary powers to confuse Byakuya. To even the odds, Senbonzakura combines his power with Byakuya. They then used their Bankai's Senkei form to counter the illusions.

Shocked that Byakuya could still fight him as an equal, Kōga shouts that it is impossible for them to be so powerful. Byakuya merely says that it is because he fights as one with his Zanpakutō, thus allowing him to achieve his greatest strength. Kōga, on the other hand, cast away his full power to satisfy his ego. Refusing to listen to reason, Kōga is determined to finish the battle, forcing both warriors to go for a final clash. In the aftermath, Kōga is defeated. Refusing to admit defeat, he calls for Muramasa to aid him. But like centuries ago, he is shocked to see that Muramasa does not respond, forgetting that he had already severed his bond with him. Failing to see the truth, Kōga falls into the depths of the lake and dies.

Powers & Abilities
Master Swordsmanship Specialist: Kōga was an immensely powerful combatant, even with only his sealed Zanpakutō. Back when he was only a 3rd seat officer, he was able to easily fight at captain-level and take down a large group of enemies attacking him at once. His skills are very versatile, able to use various bladed weapons with high proficiency.

Flash Step Master: Kōga has demonstrated highly proficient skill in Flash Step, able to keep on equal footing with Byakuya Kuchiki, one of the most skilled masters. In battle, Kōga has shown great enough reflexes to dodge point-blank sword attacks unscathed.

Kidō Master: Kōga's skill in Kidō is immense, able to use various forms of spells with great power and skill; all at the same time without incantation.

Enhanced Strength: Even in his physically withered state, Kōga is deceptively strong. With a single downward chop, he was able to snap his sword's blade in two.

Immense Spiritual Power: While not a noble by blood nor of considerable age, Kōga possessed great spiritual power even when only a 3rd seat officer. Ginrei, the 6th Division captain at the time, states Kōga's power vastly surpasses his own. He displays a massive reiatsu, even after being sealed away for several centuries. His reiatsu is purple in color. His skill and control at using his spiritual energy allows him to perform a variety of abilities.


 * Illusions: By channeling his spiritual energy into his opponent, Kōga is able to distort the target's perception, effectively making a person's five senses unable to properly register what is happening. This power can be negated by one using their spiritual energy to close off their emotions before the hypnosis takes place.


 * Spiritual Threads: Kōga is able to form invisible spiritual threads to bind his opponent in place. While powerful, these threads can only be manifested through a reflection of a reflective surfaces such as a building's windows or clear water, where they can be seen.

Zanpakutō
For the manifested spirit that appears in the Zanpakutō Unknown Tales arc, see Muramasa (spirit).


 * Kōga's Zanpakutō takes the form of a katana with a dull red sheath, purple hilt-wrapping and a guard in a shape similar to the Kidō Corps' emblem, consisting of a circle with a pentagon-like shape in the center and three points protruding from the edges evenly spaced apart. Muramasa is an illusion-type Zanpakutō.


 * Shikai: The release command is "Whisper" (囁け, sasayake). Muramasa shines with bright purple light to engulf a considerable radius, affecting any and all targets within it.
 * Shikai Special Ability: Upon release Muramasa glows purple and releases a 360 degree wave of purple energy into the surrounding area causing all Zanpakutō in that area to turn on their wielder. The Zanpakutō will move on their own against their wielders will and attack their allies or even turn against their own wielder. This power is shown to effect around 10 individuals at once.

Muramasa can break into the inner world of targets, similar to how a tape-worm leeches off its target, and forces them to bend to the user's will. This is done by removing the energy stability between Shinigami and Zanpakutō, leaving the spirit confused and allowing Muramasa to forcibly release the Zanpakutō spirit's negative emotions. .

It can cause a Zanpakutō's spirit to abandon its master and attack them.

The only way to combat against Muramasa's power is by understanding how the Zanpakutō works and sealing one's "heart" against it. Though in order to block the attack in that state one must have incredible reiatsu and concentration. In addition, one must be able to still fight in that state.


 * upon a large explosion of spiritual energy, Muramasa manifests its true form into the real world. Muramasa himself has the ability to manifest in his true form and even can manifest himself at a distance from his master, able to hear his call from wherever he is. Muramasa can also manifest his sealed sword form and engage his powers independently of Kōga's command.


 * Zanpakutō Manifestation: Muramasa generates a burst of energy that affects the Zanpakutō of all in the vicinity. When this takes place, the Zanpakutō of other wielders glow with a purple light. Their Zanpakutō spirits then manifest, typically as tangible shadowy figures from weaker Shinigami and with greater individuality and power from stronger Shinigami. He achieves this by awaking the natural instincts of the Zanpakutō and warping them, causing the removal of the ties that link them to their Shinigami.


 * Bankai: Not Achieved