Kojin Kozu graduated from the painting department of the Tokyo Art School Western. He won the first prize at the 9th Bunten exhibition in 1915 for his painting Train and continued to attend official exhibitions. He later went to Europe for several years for the Ministry of Commerce. During this time, he studied at the Royal Academy in London and the Académie Julian in Paris and also visited Germany, Italy, and Switzerland. Kozu returned to Japan in 1923 and joined the group Kōzō-sha (Sculpture laboratory), led by his friend Sogan Saito (1889-1974), becoming the head of the painting branch. In 1932, Kozu traveled to the United States for the Olympic Arts Competition. After 10 years, he left Kōzō-sha and founded Midori chimata-kai (Greenery Association), later called Sō-gei kyōkai (Art Association), which in the 1950s merged with Daiichi Bijutsu Kyokai (First Fine Arts Society).