Joji Obara was born in 1952 to an impoverished Korean family in postwar Osaka. His father had been a scrap collector, then a taxi driver who worked his way into owning a fleet of cars and a string of pachinko parlors from which he amassed a fortune. Perhaps mindful of the discrimination faced by Koreans, when the young Obara葉hen known by his Korean name Kim謡as asked to pen a farewell sentiment in his junior-high class yearbook, he wrote: "Upbringing is more important than family name."
At 15 he was accepted into Japan's most 駘ite high school, a Yokohoma prep school affiliated with prestigious Keio University. To facilitate Obara's entry to the school his father purchased the Den'en Chofu mansion and sent the boy to live there with a maid. When Obara was 17, his father died, leaving holdings in Tokyo and Osaka to his son.