Kiyoshi Nagai, better known as Hiroyuki Tajima, was born in 1911 in Tokyo, Japan. He graduated from Nihon University in 1932 and in 1943 from the Western-style painting division of the Tokyo School of Fine Arts. Nagai had a great interest in the Western Dada and Surrealist styles. He received additional training on mokuhan from Nagase Yoshi, one of the early Sosaku Hanga artists. He also studied fabric dyeing with Hirakawa Matsugoro.
Nagai produced his first print in 1946. During the same year he joined the Bijutsu Bunka Kyokai, a group that helped to bring abstract and Surrealist painting back to Japan after the war. During the 1960s and 1970s, Nagai developed his abstract style of prints made of dense, rich pigments on complex surfaces formed by building the block up with various materials. He drew inspiration from the ideals of East Asian calligraphy, traditional Japanese painting structures and Zen Buddhist beliefs.
Nagai became a member of the Nihon Hanga Kyokai, (The Japanese Print Association) in 1963. In 1964 his work was shown in the Tokyo Biennale.