Zangetsu (Zanpakutō spirit)

After temporarily becoming a Hollow, an 'evil twin'-like of Ichigo was born in his mind, thus becoming his 'Inner Hollow'. 'Ogihci Shirosaki', as he is often referred to by fans, often surfaces during battles and temporarily takes control of Ichigo's body, enhancing his speed, strength, and durability, much to the latter's anger and/or annoyance. However, with the help of the Vizard (others who also have inner Hollows) Ichigo is able to overpower his Hollow and utilize his power without risking him taking control. 'Ogihci' is also the longest-running villain in Bleach history, randomly appearing in almost every single story arc, including the Bount arc and the Amagai arc. He was also the central antagonist in the Vizard arc. His presence can also be felt throughout the Hueco Mundo and Captain Amagai arcs whenever Ichigo dons his inner hollow's mask to fight tough opponents like the Espada. He had disappeared after Ichigo defeated him in his Inner world. He will most likely return as he said if Ichigo wanted to control his power then Ichigo shouldn't die before he shows up again. Implying that Ichigo has yet to fully master his Vizard mask and the Hollow may return during Ichigo's fight with Ulquiorra.

Appearance
His overall appearance is practically the opposite of Ichigo, especially in his clothing. While Ichigo wears a black standard Shinigami uniforms, his Hollow self wears a white shinigami uniform with black cloth belts. His skin and hair are also fully white and his eyes are black (on contrary to humans' white eyes) with yellow iris. His overall white color has led to the creation of his fan-name: "Shirosaki" (a play on his white color, Ichigo's last name being Kurosaki, "kuro" meaning black and "shiro" meaning white).

When the Hollow was introduced for the first time in the anime, he had black teeth rather than white as shown in the manga, obviously to further signify the difference from Ichigo. However, this was later changed to normal white when he appeared again in Ichigo's inner world (see above).

He also has his own version of Zangetsu, Ichigo's Zanpakutō: On contrary to Ichigo's black cleaver with silver edge wrapped in white cloths, his Zangetsu is silver with black blades and black wrapping cloths.

Abilities
His real-world full hollow appearance (seen in episode 123) is that of a humanoid beast with bulging, muscular legs, a mask with red stripes down one side, some of Ichigo's hair along his back and head, and a long tail with a red tip. His left arm is a large claw with which he appears to be able to fire energy beams of some sort. He has super-speed regeneration, and the ability to grow extra appendages. And his right arm is a point, which can be used to impale enemies. It is also seen in episode 123 to be used as a super-Cero charger. This cero is pink, unlike the normal red. He is also apparently able to fire out a tentacle with a large mouth at the end, which would presumably be used to catch fleeing souls were the hollow allowed to run rampant. It is suspected that he has many more abilities, but many are seen in episode 123. His body is covered in a hard, chitinous shell, unlike many other hollows. If Ichigo were ever to turn into a complete hollow, it would be the end of the world, according to the Shinigami.

His real world partial hollow is only seen as a mask covering part of Ichigo's face and steadily growing larger. However, in this form, unlike in the full one, Ichigo is merely unconscious and the hollow is stepping into the void, controlling his body. He forms a hollow hole in Ichigo's body when transforming into a full hollow in episode 123.

Zanpakutō
His Zanpakutō is identical to Ichigo's but in reversed colors. He has shown Ichigo different kinds of moves in the series using either his Zangetsu, or Ichigo's. The first was with Ichigo's Zangetsu, and he had demonstrated throwing, and spinning Zangetsu by its cloth. The second was with his Zangetsu, and it was using a Bankai Getsuga Tenshou on an enemy at point blank range. Ichigo had used this method twice in his second fight with Grimmjow.


 * Shikai: The shikai form of Zangetsu resembles an over sized, though more elegant, cleaver blade without a hilt guard. The sword is as tall as the inner hollow is; 1.75 meters, and has a silver blade with a black edge. The inner hollow carries his Zanpakutō on his back by the cloth wrapped around the handle. When not in combat, the cloth extends to cover the rest of the sword and falls away when necessary, shrinking back to a manageable size. The cloth can also be used to swing the weapon like a flail and toss it at opponents, and is one of his preferred uses is rarely done.
 * Special Ability: Zangetsu's special ability is the, which fires concentrated energy blasts from the tip of the blade in the shape of a crescent moon.


 * Bankai: : He learns his bankai at the same time as Ichigo, and just like Ichigo's, his bankai shrinks his sword down to a daitō (Japanese long sword) with a completely white blade similar to Rukia's own Shikai. The handguard is in the shape of the manji (which is the kanji for "ban," meaning "full"). The cloth wrapped around the hilt is replaced by a short chain with a broken link, similar to that of a plus spirit. In addition to his sword, his robe is replaced with a long-sleeved, ankle-length white coat with black lining that is closed at his chest. His bankai is a compression of his power, rather than a vast expansion as other bankai are. This hugely compressed power enables the inner hollow to move at high speeds exceeding those of flash steps, and gives him matching agility and reflexes, allowing him to use his natural strength to its limits. Furthermore, the fact that all of his energy is "compressed" means that usage of his Bankai doesn't expel as much spiritual power as other Bankai from the point of activation; thus allowing him to use Tensa Zangetsu at a much longer duration than other Bankai users of his level. With enough usage and acquired height, he can even appear as though he is flying. During the times when he took over Ichigo's body it was shown that his control and power were far greater than Ichigo's.


 * Bankai Special Ability: Zangetsu's special ability remains Getsuga Tenshō. When used with his bankai, these blasts are white with a red outline and their path can be controlled, with augmented power and speed. He can also use it with his hand(s). During Byakuya Kuchiki's fight with Ichigo, the Hollow took over and was actually the first to perform it. Due to this fact, the more Ichigo uses the move, the easier it is for the hollow to take control.

Personality
His most distinguishing feature is his maniacal laughter and lunatic grins. He is brutal and sadistic, his only reason for existence being to take over Ichigo's power and his body to use it to kill everything and anything he sees. He taunts Ichigo as being weak and unsuitable for being a counterpart of, though he relishes the idea of taking Ichigo's powers for himself. He battles like a berserker, ignoring injuries and overpowering his enemies with brute strength and force. He also protects Ichigo's body when he is about to die, because if Ichigo died, he would too.

Control over Ichigo's powers
The Hollow is capable of taking over Ichigo's body and powers when Ichigo falls unconscious in a fight. When he does this, a white mask starts forming on Ichigo's left side of the face and the eyes blacken. (Note: in episode 82 of the anime, his right eye was normal in color. However, in other countries, this was corrected to the proper black.) He is able to ignore most of the injuries Ichigo has sustained up to that moment, and starts fighting like a berserker (much as he does when battling Ichigo in his inner world) with fearsome strength and speed, much more than Ichigo's already abnormal levels.

In the Vizard arc, Ichigo underwent a full transformation into a Hollow. This full Hollow is shown as a white humanoid lizard with long orange hair and slit eyes seen through the eyeholes on its full mask. It displays powerful abilities such as instant regeneration, growth of additional body appendages, and an very exceedingly powerful Cero.



Physical Abilities
The Hollow is seen to be much more powerful than Ichigo, overpowering Ichigo very easily. His physical strength is already much greater than Ichigo's, while he gains any power that Ichigo does, evidenced by his use of Bankai. He is capable of deflecting Ichigo's Getsuga Tenshō with his unarmed left hand, and his own Getsuga Tenshō is incomparably stronger than Ichigo's. His actual limit is unknown, as he was never in any case seen fighting with all his strength.

After Ichigo subjugated the Hollow, he started using the Hollow powers.