Ryoichi Yazu was a Japanese inventor. He is best known for his invention of Japan's first mechanical calculator.
Ryoichi Yazu was born in Buzen, Fukuoka as the son of a village mayor. He attended primary and middle school in his home village of Iwaya and the city of Buzen. At the age of 16 he left middle school and travelled to Osaka to pursue his interest in flight, studying mathematics and engineering at a private school in Osaka.
At the age of 22 he returned to Buzen and began work on a thesis on the mechanics of flight. Two years later he brought the thesis and a model of his calculator on a visit to the novelist and army physician Mori ogai.Impressed, Ogai wrote recommendations that led to a special research position at the Tokyo Imperial College of Engineering, where he worked on the design of a propeller-driven airplane.