Kastro

Kastro (カストロ, Kasutoro) was a prominent fighter in the Heavens Arena and an apparent celebrity. He lived on the 200th floor of Heavens Arena, with the intent of accumulating enough wins to become a Floor Master. His only appearance is the lead up to his rematch with Hisoka.

Appearance
Kastro is a well-built man who has green eyes and loose white medium-length hair that reaches down to his upper back. His dressing attire consists of a yellow hood-less cloak over a white robe with black outline, and white pants that are tucked into his grey boots. In the 1999 anime adaptation, his design is identical for the very most part with the differences being his color scheme and the shortening of his cloak.

Background
Two years prior to the start of the series, Kastro fought Hisoka in the Heavens Arena. He scored a knockdown and won three points (the only one to do so against Hisoka), but was ultimately defeated. After this, he trained rigorously to improve his Nen, and gains nine wins. He then challenges Hisoka for his tenth win, confident he could defeat him. Kastro kept his Doppelganger ability hidden.

Heavens Arena arc
Kastro makes his first appearance during an interview before his match with Hisoka. Interested in meeting Kastro; Killua manages to sneak past a guard and makes it to his room. As Killua spots Kastro sitting in his room, Kastro mysteriously appears behind him and inquires what his business is with him. Killua baffled now that the chair he saw Kastro sitting in was now empty. claims he wants an autograph. Although happy to oblige to the request, Kastro easily deduces Killua's true motives and foresaw his arrival, for using Zetsu upon entering the floor. Curious Killua inquires how Kastro managed to disappeared so quickly, but Kastro keep it as secret. Kastro returns to his room, but not before saying he'll wait for Killua at Battle Olympia. Killua however has no interest in fighting him.



Before the match with Kastro and Hisoka began. Kastro thanks Hisoka for baptizing him from their previous match 2 years ago, because his baptism he's accumulated greater strength, which is enough for him to beat him with. The referee begins the match and Kastro quickly gets the first hit. Surprised by this, Hisoka believed he avoided the attack as Kastro demands Hisoka to get serious. Kastro claims he's not the same as he was 2 years ago and won't hold back any longer. Hisoka merely mocks Kastro about being serious. So Kastro takes another swing at Hisoka who dodges, but gets hit with another unforeseen attack. The unforeseen attacks continue until Kastro manages to knockdown Hisoka, gaining him a 4-0 lead. Regaining his composure, Hisoka claims to have seen Kastro disappear. Hisoka tries to deduce how Kastro managed to pull such a feat on him so far. Kastro however tries to instigate Hisoka to attack him and uses his Tiger Bite Fist Hatsu to rip off Hisoka's right arm, whom sacrifices it willingly.

Kastro then taunts Hisoka for sacrificing up his arm would act in his favor he's wrong. However Hisoka is confident it will and then uses a leg sweep on Kastro, while catching his severed arm in mid-air. Hisoka then proclaims that this whole time Kastro has been using creating a Conjured double to help preform feint attacks. Kastro confirms Hisoka's deduction and has his "Doppelganger" appear next to him. After a brief conversation Hisoka and Kastro have of the strength and properties of Kastro's "Doppelganger". Kastro then assumes the position of his Tiger Bite Fist again and proclaims he'll use his True Tiger Bite Fist to rip off his left arm. Hisoka however becomes excited by Kastro's declaration and starts to eat the flesh off his severed arm a bit, irking Kastro a bit. Hisoka then covers is severed arm within a cloth and makes said arm disappear, making a bunch of playing cards scatter across the arena. Hisoka then has Kastro pick a card and mesmerize it and after calculating a mathematical equation pulls an ace out of the severed part of his shoulder arm.



Agitated Kastro uses his double to take Hisoka's left arm, whom again willingly gives up. However Kastro is shocked to Hisoka's right arm reattached and deduces that Hisoka used his Nen to reattach his arm. Hisoka then praises Kastro's skill, but predicts he'll dance himself to death. Aggravated, Kastro and his Doppelganger charge towards Hisoka, but as they separate Hisoka figures out the real Kastro, because the Doppelganger doesn't reflect any damage dealt to it. Frustrated by this reveal, Kastro tries to ambush Hisoka from behind, but is struck in the face by Hisoka's severed left arm. Stunned by the attack Hisoka throws his sharp playing cards at Kastro killing him on impact. Hisoka claims by squandering his memory to create a Conjured duplicate of himself that also can be controlled and use complex moves, Kastro caused a "Memory Overload", creating his demise.

When Wing teaches Gon, Killua, and Zushi about the individuality of Nen, he reveals that Kastro was an Enhancer. However since he chose to create a Hatsu using both Conjuration and Manipulation, which aren't compatible with Enhancers. Although he mastered this Hatsu through strenuous training, he overexerted his talent.

Abilities & Powers
Kastro demonstrated himself to be an excellent fighter with considerable combat skills, which many rank on par with those of a Floor Master. Proof of it is the fact that he never lost a single match except the two against Hisoka, who allowed him to survive because he had taken interest in his potential. His fighting style combines his advanced hand-to-hand techniques with the deception granted by his clone. Kastro is also very adept at reading the flow of aura, even when it is not being released, as was the case when he exposed Killua's lie about not being interested in fighting just by looking at him. It is reasonable that he can use this skill in combat, too, in order to predict the moves of his opponent.

Enhanced Perception: Kastro managed to detect Killua's presence on his floor and its sudden disappearance. He claims that this is normal for a fighter of his caliber.

Enhanced Strength: Kastro is fairly strong, enough to mutilate a fellow Heavens Arena fighters using only his bare hands. He also managed to momentarily stun Hisoka with a sudden blow.

Enhanced Speed: Although most of the attacks he lands are due to his disorienting the opponent with his Double, this strategy requires a great timing and a considerable amount of speed to work, since the target must not be permitted to see two of Kastro at once lest his ability is figured out. Prior to the fight with Hisoka, this had never happened. In said confrontation, he managed to move behind the magician, and in his first appearance, he appeared behind Killua without the assassin noticing him approach (even though he might have simply used Zetsu in conjunction with his clone).

Proficient Hand to Hand Combatant: With the full degree of his abilities in this field being unclear, Kastro is still capable of performing the Tiger Bite Fist, an advanced technique that, as Killua stated, has enough power to cut down a tree if used by a master. The martial art he employs appears to focus primarily on striking the opponent with one's hands, with chops in particular. Kastro's swings are generally very wide, making them stronger but allowing skilled opponents to predict them, although this backlash is covered by his Double.

Nen
Kastro is an Enhancer, but he also has considerable skills in the Manipulation and Conjuration categories. Although his Doppelganger ability is tricky to most opponents, it has many flaws. Some of the flaws include the immense amount of focus it requires (for an Enhancer) and Kastro's inability to replicate the effects of a battle, such as dust and blood, on his clones making the deceptive and trickery aspect of the ability obsolete in a drawn-out clash. The biggest pitfall is that Kastro's over-emphasis on Doppelganger also makes him to neglect and trivialize his natural Nen category, Enhancement, where his true strength lies. Nevertheless, Kastro is certainly a formidable Nen practitioner.

Trivia

 * Most of Kastro's battle with Hisoka was omitted in Nippon Animation's anime adaptation.