Hamaguchi Yōzō was an international artist, spending nearly as much time living in Paris or San Francisco as he spent in Japan. He was the third son of a hereditary company of soy sauce makers in Wakayama Prefecture. The family moved to Chiba Prefecture when Yōzō was a child, and he entered school at the Tokyo University of the Arts as a student in the sculpture department. Unsatisfied, in 1937 he dropped out and moved to Paris. There he endeavored to learn dry point etching. He returned to Japan in 1939 as war loomed. He worked as an interpreter in Vietnam for the Japanese government during the war, again returning to Japan in 1945. From 1950, Yōzō gave his full attention to prints, returning to France in 1953 where he would research mezzotint. In 1957 Yōzō won the grand prize at the Sao Paolo International Print Biennial, as well as The National Museum of Modern Art award at the Tokyo International Print Biennial. This began a string of awards that continued through his career. Yōzō continued to live in France, except for a one year hiatus in Brazil in 1971 and 1972, but he left France for San Francisco in 1981, not returning to Japan until 1996, four years prior to his death. Hamaguchi Yōzō is most famous in his career for having revived mezzotint technique and also for pioneering color mezzotint. The largest restrospective of his work was held at the National Museum of Modern Art, Osaka, in 1985, followed in 1999 by a retrospective at the Sakura Museum of Art in Chiba Prefecture.
There is a Musee Hamaguchi Yōzō in Tokyo established in 1998. Museums holding his work include the Metropolitan Museum of Art, New York, the Bibliotheque National in Paris, the Art Institute of Chicago, the British Museum, The Art Gallery of New South Wales, Australia, the National Gallery of Art in Washington D.C., and the Philadelphia Museum of Art, in addition to LACMA.