Triton is a killer whale who befriended Black Jack.
Triton is a friendly killer whale who befriended Black Jack since the first time they met each other and even trusted Black Jack to treat him without disturbing. He is loyal and always prepare a pearl, a coral or an old gold coin to pay Black Jack for his treatments on him even though in the end, Black Jack couldn't do anything to treat his very serious injuries caused by the fishermen. He is also protective towards Black Jack when his friend suddenly attacked Black Jack and he fought with it. Even though he is friendly with Black Jack, he is never friendly with the fishermen as he always cause troubles with them by raiding their daily catch, upturned a boat and ate three children.
However, in the anime, his character is more friendly as it did not attack the ships but instead protected them from another dangerous killer whale and even saved a fisherman from drowning to death which can be differentiated with its different fin and slightly different coloring, making him kind and gentle towards humans despite still being wary of them as opposed to his manga counterpart. Triton was framed by the killer whale and mistakenly believed to have been the one attacking them but was able to finally kill the other killer whale and had his injuries treated by Black Jack.
Five years ago, Black Jack sets up his practice on the hill overlooking the beach but no one came to his place maybe due to his appearance. One day, as he was taking a stroll on the beach, he saw a killer whale lying down on the shallow waters of the cove, seriously injured. Black Jack proceeds to treat the whale and the whale kindly repay him by giving him a pearl. Since that day, they always keep seeing each other. Black Jack made a medical record about the whale and named it Triton. Less than ten days, Triton will appear, injured and Black Jack will treat him, which Triton gave a coral, a pearl or an old gold coin in return. Every time Triton is healed, he and Black Jack will go out to sea to have a swim together and Triton taught Black Jack how to swim in speed.
One day, Triton bought another killer whale to meet with Black Jack but things didn't went so well as the killer whale tries to attack Black Jack but was rescued by Triton. Triton visits Black Jack again but this time, he appeared badly injured which Black Jack think it could be a harpoon. At the city, he heard fishermen are talking about a killer whale wearing bandages keeps raiding their daily catch and promises they will be able to harpoon it one day. Black Jack soon realizes they are talking about Triton. Guessing the wounds are from the fishermen, he met Triton in the cove and advises him not to return to the fishery and the cove and head out to the open seas where he will be safe from them.
In the manga, Triton overturned a boat and ate three kids, which angers the fishermen. They had enough of Triton and set out to kill him for good. Black Jack never saw Triton for a month but when he saw the fishermen boats are heading towards sea, he fears that Triton could be in danger and race towards the cove, hoping Triton won't be there but it did. Triton appeared in his bloodied form, held a pearl in its mouth, waiting for Black Jack to treat him but Black Jack refuses saying that he couldn't do anything about it. Stubborn, Triton kept returning to the cove, weak and holding a new pearl. A few days later, Triton passed away in the cove, surrounded by the pearls he bought which sank to the bottom of the cove.
The anime ends this differently, possibly to be more kid friendly and also to ensure Triton was a more sympathetic character. In the anime, while the fishermen did see a killer whale with bandages, the whale that attacked them was a different one and as it turned out Triton was protecting Black Jack and the fishermen from the dangerous killer whale (in the manga Triton introduced this whale to Black Jack but in the anime the two were enemies and Triton was attacking him to protect the fishermen). When the dangerous killer whale, which can be easily differentiated with a different fin and slightly different coloring attacked one of the ships and caused one of the fishermen to go overboard, it was Triton who saved him. The fisherman's son believed Triton did this and sought revenge, injuring Triton in the process. However, when the dangerous killer whale revealed himself Black Jack came in a boat of his own just in time to save them and Triton killed the other whale. Later Triton returned to the cove to repair its injuries which Black Jack did, but told Triton to leave as it was going to be the real last time. As he tells this story to Pinoko, he sees a killer whale jumping in the water and realizes it is Triton checking up on Black Jack to see how he was.
He appears in the Black Jack 21 series saving Black Jack from an assassination attempt as he is nearly drowned by assassins out for his life.
He has the appearance of a typical killer whale. He is roughly three to four times larger than Black Jack and has a damaged fin. His body is blue with scars and a white underbelly and white spots near his face.
His anime counterpart is considerably kinder towards humans than the manga counterpart as it protected humans in contrast to eating them, though both counterparts were still wary around humans and fishermen.