Taikichiro Mori had his first taste of wealth when he became a real estate investor at the age of 51. In 1959, he founded the Mori Building Company, which is still owned by his descendants today.
The business made him the richest man in the world by 1992, when his net worth reached $13 billion, according to Forbes. That's the equivalent of $29 billion (£22bn) in today's money.