The family firm, Mori Building Co, owns 83 buildings, most of them office blocks standing on some of the most expensive land in central Tokyo. He enjoyed the nickname 'Tokyo's Landlord'.
When he was swept to the top of Forbes magazine's wealth rankings by the strong yen of the late 1980s he reacted with embarrassment and scepticism, insisting he wasn't really worth dollars 13bn. 'I owe the position to the bubble economy. When the bubble bursts, we will know the true value of assets,' he said.
Mori's public modesty and the simplicity of his private life - he neither drank nor smoked and lived in a home that was extremely small by billionaire standards - belied the sophistication of his business abilities. He was one of the few academic economists to make a fortune.
The son of a rice trader, who managed property on the side, he took a university degree in 1928 and went on to become head of the School of Commerce at Yokohama City University, specialising in trade theory.
He was 55 before he gave up university life to practise full- time what he had preached. Circumstances favoured him: Tokyo, levelled in the war, had begun its extraordinary industrial growth and desperately needed offices. The family firm was already booming. Mori steadily acquired sites and raised buildings, naming each after himself: Mori No 1, Mori No 2, Mori No 3 and so on. Only after Mori No 45, when city centre geography was becoming impossibly confusing, did he go over to names.
Mori was renowned for his long-term thinking. He would wait many years to clear a single site, buying up each property as it became available. His biggest project of the 1980s, Ark Hills, was built on land he began acquiring almost 20 years earlier.
Like many of Japan's post-war business barons, he viewed his work as part of a cause: the reconstruction and remotivation of the country. He liked to portray 'development' in the most positive sense, clearing slums and replacing them with modern, clean, efficient buildings. He was criticised, however, for demolishing the traditional Tokyo of narrow streets and one-man businesses.
Taikichiro Mori died of heart failure at a Tokyo hospital. He is survived by his wife Hana - theirs was an arranged marriage in 1932 - two sons, Minoru and Akira, both in the family firm, and a daughter, Aiko.