His ringname is Jack Hammer (ジャック・ハンマー, Jakku Hanmā).
He's driving force is wanting to defeat his father, Yujiro Hanma, to avenge his mother who was raped by him. Jack turned into a monster without balance who only cares about becoming stronger to take revenge.
He sees his brother, Baki Hanma, as a rival, but also likes him deep in his heart as they have the same goal in surpassing Yujiro.
Jack trained so hard to reach his goal that his muscles deteriorated in the process. He took super steroids to attempt to strengthen his muscles but managed to destroy his body even further in the process drastically reducing his life expectancy.
Due to Jack's intense daily training, which supplemented by his super steroids, he managed to become extremely muscular. His physical features include blue eyes, a piercing gaze and short blonde hair and rather large eyebrows. He's often wearing a blue t-shirt, long jeans or shorts.
Baki the GrapplerEdit
Like his brother Baki, he has since childhood wished to surpass his father Yujiro Hanma in strength and martial ability. His obsession to defeat his father led to extreme overtraining at various fighting gyms which led to the deterioration of his body. He wasn't much more than skin and bones because his body had been damaged by overwork. For example, Jack would punch sandbags for over 12 hours without eating, resting, or even using the restroom. He claimed he will never be able to defeat his father with normal training. After his encounter with the Yujiro-inspired scientist named Dr. John who witnessed Yujiro killing a polar bear. The scientist promises him great results if he tries using a special drug. He 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.
Most Evil Death Row Convicts SagaEdit
After the Maximum Tournament, Jack has Kureha Shinogi perform surgery to enlarge his bones where multiple of his bones were broken and he had his limbs amputated 8 times.
One of his main techniques is the biting, and he can bite hard enough to easily crush wood with his teeth. He claim that his teeth can tear a coconut. Although he lost all of his teeth, his bite can still damage Izou Motobe when he wear a chain mail made of aramid fibers, which is made for plane and tire. His body is strong enough to surpass drugs, even though he used abnormal amount of drugs. His strength is shown many time in the story: defeating the convict Sikorsky in a telephone box and withstanding his knuckle slash in the underground arena, taking many blows from Mohammad Alai Jr and defeating him, cutting his tongue in the process, fighting with Pickle and making him run away in fear of the only creature that scares him, a wasp. Despite using brute force to fight, Jack is very tactical and smart enough to counter and outmaneuver his opponents. For example, he found the weakness of Aiki after being thrown many times and used a similar move to defeat Goki Shibukawa.
- He is based on the legendary British professional wrestler Dynamite Kid.