He was voiced by Kong Kuwata.
At the start of his life, P4 was born as a normal dog of mixed breed. However, after prolonged time of laboratory testings and gene mixing, he grew a monstrous size of about 3. 6 meters, bigger than any existing dog breed with a weight of about 450 kilograms. Due to his escape before all the tests being performed on him can be finished, he also looks a little incomplete, having exposed muscle and nervous system on the right underside of his chest. While his face and body resembles that of a giant, muscular dog, he also has a bushy mane like a lion. Overall, he has a black top and a yellowish-brown underside. His ears are also black and he has brown facial marks. His eyes are olive green (sometimes white in hte manga) and can glow with reddish light. His hips have chains attached to them from his time as a test subject.
Kaibutsu started out as a normal gaurd dog in an experiment ground in Iwate Prefecture. However, he was soon taken away to be an experiment himself and through the experimental testings, he slowly became the monster that he was. The experiments were incredibly painful and he came to loathe what he was becoming.
The only dog to provide comfort to him was Jerome, a German shepherd and another gaurd dog, since the other gaurd dogs viewed him as a freak. Through Jerome's encouragement and emotional support, Kaibutsu managed to tolerate five years of experimental torture. However, his sanity finally snapped and hebroke free, driven to insanity by the pain and feeling betrayed by his owners. Though Jerome had initially supported him, he attacked Kaibutsu once he saw the damage he was doing, and Kaibutsu, in his quest to escape, injured Jerome and many of his fellow gaurd dogs. He also killed the laboratory's owner, having the first taste of human blood, something which fuelled his bloodlust and hatred towards humans, and his feelings of friendship and loyalty disappeared with his mutation.
He went into hiding in the Ohu Mountains and while he first saw himself as another dog, the fright and a violence he got as a reaction from the the resident dogs of the Ohu Mountains made him feel like a freak and an outcast, fuelling his hatred. He became a maneater and a dog-killer, hating both kinds with passion and knowingly living up to the reputation as a monster he had gotten. He admired his strength and viewed other dogs as weaker creatures meant to be killed if they messed with him. He massacred the dog and human population of Ohu and took up residence in Gajou, leading a fairly directionless life and spending his time solely by killing and eating dogs and humans.
Powers and Abilities
Due to his mutation, Kaibutsu gained enhanced speed, being able to keep up with motorbikes despite his size. He also had strong jaws which he could use easily to crush his opponents or hold them in a way that is torturous yet non-lethal. His hide was also incredibly tough, especially his top, which couldn't be torn by teeth or damaged by rocks. He also had increased vitality which allowed him escape being crushed by the rocks of Gajou after his second encounter with Weed.
Ginga Densetsu Riki
Ginga: The Last Wars