After relocating to France in 1929, Okamoto gradually moved away from the pure abstract world and discovered surrealism. In 1940, he returned to Japan. After the war, he immediately propounded his principle of “polar opposites,” placing him at the forefront of Japanese avant-garde art theory. In 1970, he created Tower of the Sun (Expo’70 Commemorative Park) for Expo’70 in Osaka. His famous catchphrase, “Art is Explosion,” expressed his personal view of art as being something that rejects communication or understanding, that goes beyond effect and result or historical, cultural and temporal frameworks, constantly expanding without objective. This work, Tree Man, overflows with a dynamic life force, continually proliferating in a free and unrestrained manner.