He was born in the mountainous and rural region of Gifu, Japan. He began learning mathematics in middle school, reading texts in English since none were available in Japanese. After attending a high school for gifted students, he went on to the University of Tokyo, at that time the only university in Japan. There he learned mathematics from such European classic texts as Salmon's Algebra and Weber's Lehrbuch der Algeba. Aided by Hilbert, he then studied at Göttingen. Aside from his work in algebraic number theory he was notable for the quantity of textbooks he wrote in Japanese.