Black Jack is hired to act the part of a man's son to operate on his ill older brother. Reluctantly, Black Jack agrees. While waiting to meet with him, the story of the two brothers is told to Black Jack and Pinoko. As a promise to their dying father, the elder brother worked hard to send his younger brother to become a doctor, though he was obviously not cut out for it. Under the pressure, the younger brother ran away and started his own successful company, but his son is revealed to be studying in America to become a doctor...