Born in the ancient pottery town of Shigaraki, Kohyama began working at a ceramic factory when he was fifteen. He performed chores at Oumi Kagaku Touki, the largest factory in Shigaraki that was influenced by Scandinavian design, during the day and trained in basic ceramic throwing techniques in the evenings at a vocational school. In 1955, he apprenticed under Sakuzo Hineo (1907–1984), a potter from Ueno, and began to concentrate on tableware. In the 1960s, Kohyama started collaborating with designers and architects to create ceramic tile installations. However, he is now best known for his vessels, both traditional wares like tea bowls as well as more experimental, sculptural forms. Many of Kohyama’s pieces are suitable for ikebana, the art of flower arrangement in which he himself is highly skilled. He developed and continues to hone his creative process of cutting away clay with metal wires. He prefers to fire his works in a wood-fired anagama kiln. He has come to Cleveland three times to serve as an instructor for the Cleveland Institute of Art and for Kent State University: in 1993, 1999, and 2008.