family of Japanese businessmen who built two vast corporate empires as Japan made the transition from a manufacturing-based to a service-based economy in the late 20th century.

Born into a peasant family, Tsutsumi Yasujiro (b. 1889, Shiga prefecture, Japan—d. April 26, 1964) graduated from Waseda University in 1913. He founded the Kokudo Keikaku land-management company in 1918 and began buying real estate on a significant scale in the 1920s. He also entered politics, being elected to the House of Representatives in 1924 and reelected 12 times after that. Yasujiro laid the basis of his fortune in the years immediately following World War II, when he was able to buy large tracts of land in Tokyo and other important locations at bargain prices from ruined aristocrats and others who had been impoverished by the war. He then began building suburban railways, resorts, hotels, department stores, and golf courses. His various business concerns were unified under the Seibu Railway Co., Ltd. His political career climaxed when he served as speaker of the House of Representatives in 1953–54. At his death in 1964 he was one of the wealthiest men in Japan.

Yasujiro fathered numerous children by three successive wives and various mistresses. Tsutsumi Yoshiaki (b. May 29, 1934) inherited the bulk of his father's fortune, becoming president of Seibu Railway Co. and the principal shareholder in Kokudo Keikaku. The owner of the largest private railroad company in Japan, Yoshiaki built many hotels, amusement parks, resorts, golf courses, and sports centres adjacent to his network of railway lines radiating from Tokyo. By the early 1990s he was the largest private landowner in Japan and, owing to the spectacular rise in Japanese real-estate values, one of the world's wealthiest people.

The other prominent son of Yasujiro was Seiji (b. March 30, 1927), who in 1964 received only a single department store as his share of his father's inheritance. But Seiji was able to parlay this property into the Seibu chain of luxury department stores, which by 1990 had become Japan's largest department store chain. Seiji also built up The Seiyu, Ltd., a large chain of discount department stores, and he diversified into a vast array of other retailing, financial, and leisure-time services. His more than 100 companies were unified in the Saison Group conglomerate, which in 1988 purchased the Inter-Continental Hotel chain of luxury hotels in the United States, Europe, and the Middle East. An unconventional and artistically inclined businessman, Seiji was also a well-known author of poems and short stories under the pen name of Tsuji Takashi. Yoshiaki and Seiji kept their corporate empires separate and in fact were said to be intensely competitive rivals of one another.