Black Jack (TV) EP37 - The Dolphin and the Pirates

Black Jack is kidnapped on his way home after a job and forced to operate on a thief who had been injured during a large job. The brother of the wounded man and the third member of the group take Black Jack out to see on a boat, but they become lost. With the wounded brothers condition deteriorating and the third bandit slowly succumbing to madness due to hunger and fear, a dolphin is brought onto the boat. Black Jack saves the dolphins life and lets it go, the dolphin in return guides the boat back to Japan, at the cost of its own life.