'Jack Hanma (or Jack Hammer) (ジャック・ハンマー) Baki's half brother who, like Baki, must follow the Hanma path. He's a pitfighter from Canada and the son of Yujiro and a Canadian soldier woman who Yujiro met in Vietnam during the Vietnam War,She had mislead him into thinking she was a freedom fighter who opposed America's War crimes against Vietnam and went everywhere Yujiro did leaving destruction in their wake particualrly toward the American forces, after capturing a base and with it ready to be blown to pieces Yujiro decided to reveal he had known all along who she was, a secret agent in the employ of the United Nations sent to investigate Yujiro's true strength the ensuing explosion destroyed everyone in the base and outside it except Yujiro and Jack's mother who's name is revealed to be Diane Neel, this was the first known time that the Demon face had appeared on Yujiro's back, he quickly beat Diane for her deception and then raped her leading to the birth of Jack as such Jack has developed a mental complex where he is grateful to and loves his mother for caring for him he himself curses his entire existence knowing he brings his mother such pain and so he has made it his life's mission to destroy his father even at the cost of his own life. Like Baki, he has since childhood wished to surpass his father Yujiro in strength and martial ability. His obsession to defeat his father led to extreme overtraining at various fighting gyms,which combined with a lack of food and sleep led to the deterioration of his body. He claimed he will never be able to defeat his father with normal training. After his encounter with a Yujiro-inspired scientist who witnessed Yujiro killing a polar bear, Jack received from him a concentrated formula of steroids to match his overtraining and gained immense power in the process and Jack had become even more mentally unstable. As a pitfighter one of his main techniques is biting, and he can bite hard enough to easily crush wood with his teeth. He fights Sergio Silva in round 1, and Misaki Kengo in round 2 before beating the undefeated Andre Andov Garrand in round 3. In round 4 he fights Goki Shibukawa and he then fights Baki Hanma in the finals of the Maximum Tournament where he congratulates his brother for a well fought victory. Afterwards, he takes on his father and is soundly defeated. Makes an appearance in the 'Search of Our Strongest Hero' series and battles against the Russian convict Sikorsky and Mohammed Ali Jr. He is treated by Kureha Kosho by having his limbs extended, making Jack Hammer even bigger than when he fought in the Maximum Tournament . In the English dub, his name has been changed to Jak Xamma (pronounced "Zah-mah"). He reappears in Baki: Son of Ogre, in the military base where Pickle is captive, along with 7 other fighters (Doppo Orochi, Katsumi Orochi, Jyaku Kaiou, Retsu Kaiou, Kureha Shinogi, Gaia, Goki Shibukawa). He is currently fighting Pickle in the Korakuen area. First they do a "bite challenge", and Jack gets his jaw's flesh stripped off, leaving his teeth and muscles. It appears Jack has taken drugs once again, and he manages to hit Pickle many times while also getting his right ear bitten off. Then, he get a clean hit from Pickle with full power to the jaw, and get his jaw as well as his teeth and parts of his cranium broken. However, he choose to continue to fight, making Pickle run out of fear, but then Jack is K.O. once again, and tied to the flag of a building. Upon learning this, Jack has a mental breakdown. He is based on the legendary British professional wrestler Dynamite Kid.
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