Black Jack is a surgeon with unparalleled surgical skills. He reattaches and transplants limbs, performs near-perfect cosmetic surgery, and even cures the terminally ill. He operates without a license, preferring to remain in the shadows where he can operate freely and without rules or corruption.
He is also a skilled fighter and can use his scalpels as weapons; he once clogged the barrel of a gun with a scalpel from some distance, for example. He is also known to play the card game blackjack and to take part in other gambling activities.
A player with an ace and a “ten-card” (picture or 10), which counts to 21 in two cards, is referred to as having a natural, or blackjack. If a player has a natural and the dealer does not, the player pays the dealer one and a half times their original bet. Likewise, the dealer will pay any players who placed insurance wagers two to one.
When Black Jack was a child, he and his mother were passing through an abandoned military base when they triggered a mine that killed her and broke his neck. He was blasted into 18 different pieces and nearly died, but survived thanks to the skill of Dr. Honma.
Years later, Honma slipped into unconsciousness from cerebral softening and a cerebral hemorrhage. He had been unable to operate on his own due to his condition, but when he heard Black Jack was in the area, he asked him to help save his life. Even though the operation was likely to fail, Black Jack accepted. Despite the high risks, he was able to successfully save Honma and later visited his grave and considered it the highlight of his career.
On another occasion, Black Jack encounters Rei Fujinami, who is in a coma after being injured while ice skating. He takes her to the wealthy private hospital inherited by Tokio Umetani, although he is initially unsure of his abilities due to the fact that his previous patients were all in the same predicament as Rei and all died from their injuries. He eventually succeeds in treating her, but he later regrets it after seeing the dying Ajun.
While the majority of Black Jack’s patients are free, he occasionally accepts donations to cover his operating expenses. He always sets a price for his services and establishes a patient’s willingness to pay beforehand, but will sometimes make exceptions in exigent circumstances. He is also known to change his mind if he discovers a redeeming reason behind a patient’s case.