Preta Ghoul is a minor antagonist from the manga Black Cat and its anime adaptation. He is one of the latest members of the Apostles of the Star to be introduced in the story. In the manga, he appears during the battle of Clarken Island only to get beaten by the bounty-hunter River Zastory. On the contrary, he appears early in the anime but he is sent to jail and only seen again on Clarken Island, where he is defeated by Sven Vollfield, one of the main protagonists.
Preta used to be a clergyman until he turned serial killer and murdered sixteen people in six months. (How and why did he went mad is never explained.) He was eventually arrested and imprisoned for the rest of his life. However, the Apostles of the Star broke him out of jail and revealed his power of Tao in exchange of him serving in their ranks. (Oddly enough, he lost his hair when he gained his power.)
Preta Ghoul is a vicious, sadistic and homicidal madman; whose name and aspect evoke a living-dead. Although his newfound power made him very arrogant, he acts in a collected and courteous, albeit condescending, fashion, even towards the foes he is fighting. Finally, he harbours never-ending gratitude and obedience towards Creed Diskenth for setting him free.
Preta's power is called "Decay". He can reduce to ashes everything that comes in contact with his ki as if life itself was taken from it. He usually fights at close range, surrounding his hands with his ki to wither everything he touches to a variable extent; but he can also fire tremendous waves of corrosive ki along the ground or breathe huge clouds of smoke-like corrosive ki. Also, he always surrounds himself with his ki to form a "Corrosive Aura" that protects him against physical attacks. At full power, his aura can reduce anything around him to dust and be used for offensive purposes as well. As such, he can only be defeated by special attacks that do not touch him directly. Moreover, he is a very skilled fighter, able to hold his own against experts in close-range fighting.
In spite of his highly dangerous power and his fighting abilities far beyond human level, Preta is very physically frail and does not seem to have trained as much as the other Apostles, as he only uses rather basic attacks and fighting patterns. Should he have trained to the full extent of his abilities, he would have been much harder to defeat. It is also worth nothing to note than his foe's fighting skills rivaled that of the Apostles and the Chrono Numbers, (the mightiest warriors alive).
Preta is first seen during the first chapters of the battle of Clarken Island, in which the Sweepers League, a group of powerful bounty hunters (including the three main protagonists), invades the Apostles of the Star's main hideout. Preta is seen accompanying Maro, when the Tao Master greets Train Heartnet, the series' hero and his fellow bounty hunter River Zastory. Maro attacks Train and Preta challenges River, who surpasses his skills and manages to punch him in the face. Preta then drastically increases the "Corrosive Aura" that surrounds him to protect himself from River's blows but the bounty hunter launches an attack called the "Sonic Fist", a punch whose sheer speed and strength cause a shockwave that hits Preta without physically touching him and knocks him out cold. Preta's fate at the end of the series remains unknown, though it is likely that the Chrono Numbers tailing the Sweepers League took him into custody or, given some Numbers' mindset, finished him off.
In the anime, Preta appears in the very first episodes. He is a serial killer who got in touch with Creed, Shiki and Maro and had his power of Tao revealed. It is not known however whether he once was a clergyman like his manga counterpart. Preta has a 18 million yens bounty on his head and is targeted by the bounty-hunter Saya Minatsuki, before he can join the Apostles of the Star. He drives Saya into a corner and prepares to finish her off, but she is saved by Train and manages to capture him and to hand him to the police.
It is revealed during the battle of Clarken Island that the Apostles of the Star broke Preta out of jail. He has completely lost his mind, mistaking every woman who comes near him for Saya Minatsuki and attacking her out of rage. Eve lures Preta by transforming herself to look like Saya and Sven engages a fight against him.
Sven manages to dodge all of Preta's attacks thanks his "Vision Eye": a special power enabling him to foresee the future. Seeing that Preta's clothes resist his corrosive ki, he rips his shirt off with a fishing pole and uses its fabric to protect his fists, knocking out the deranged murderer with ease. Sven ultimately uses what remains of Preta's shirt to bind him before locking him in a cage.