Jack is an incredibly determined and stubborn person he just doesn't know when to quit. After taking super steroids that made himself beyond unstable, Jack turned into a monster without balance who only cares about becoming stronger to take revenge.

Jack's driving force is wanting to defeat his father, Yuujirou Hanma, to avenge his mother who was raped by him.

3.2.1 Most Evil Death Row Convicts Saga.

In the fifth manga series, he is also known as the 'Biting Cyborg' (噛みつきサイボーグ, Kamitsuki Saibōgu). His ringname is Jack Hammer (ジャック・ハンマー, Jakku Hanmā). In the English dub of the second anime series, his name has been changed to Jack Xamma because of dub issues (pronounced 'Zah-mah').

Like his brother, Baki Hanma, he has since childhood wished to surpass his father in strength and martial ability. He's a pitfighter from Canada and the son of Yuujirou Hanma and Diane Neil, a Canadian United Nations operative who Yuujirou met during the Vietnam War. Jack Hanma (ジャック範馬, Jakku Hanma) is a fictional character from the Baki the Grappler series. I never once planned to live a long life! I've long been ready to exchange the strongest body ever for death.

Jack hamm golf wiki