He was professor emeritus at Hōsei University where he ran the Ōhara Institute for Social Research, and was best known as the compiler of a Lexicon of Marxist Political Economy.
Born to a paper-seller in Okayama-city, Okayama-prefecture, as the eldest son he was expected to take over the family business, and after reading Wealth of Nations he developed an early interest in economics.
The Rice riots of 1918, along with disillusionment with his work, caused him to move towards a socialist perspective and leave his job after only three months.
He maintained a system of note cards containing important passages of Marx's writings, which later helped him compile the Lexikon.
At Hōsei he participated in monthly readings of Marx which included Kōzō Uno, with whom he formed something of a theoretical rivalry.