In 1923, Omoto Torajiro began selling a mechanical desktop calculator called the "Tora Brand Calculator". This calculator was an improved version of the Brunsviga mechanical desktop calculator for which Omoto had obtained a patent. The mechanical calculator was first commercialized in the 19th century by a Frenchman, Charles Thomas, and later was mass-produced by firms like the Brunsviga Company of Germany. At the beginning of the 1900s, it appears that about 50 of these machines were imported to Japan. Later, because the Tora Brand Calculator would not sell in Japan with a Japanese name, it was changed to the foreign-sounding "Tiger" name, and became so common that "Tiger" became synonymous with the mechanical calculator. Around the middle of the 1950s, the price was ¥35,000, and it drove out foreign products for reasons of both price and performance. The cumulative number of machines sold reached a little less than 500,000 units. It was widely used until the latter half of the 1950s, and was sold until the spread of electronic calculators at the end of the 1960s. Although it was said to be for desktop use, it weighed as much as 6 kilograms.
Tiger Calculators have been preserved at the National Science Museum, Tokyo University of Agriculture and Technology, Tokyo University of Science and other institutions.