Nagare Masayuki was born in Nagasaski Prefecture. Since he was a rebellious youth and often unwilling to attend classes at the Ritsumeikan Middle School, his father apprenticed him to a master swordsmith to learn samurai discipline and later sent him to a Zen temple to study Buddhism. He eventually enrolled at Ritsumeikan University (his father was president), although his education was cut short by the war. Nagare's devotion to traditional Japanese culture, which is evident in his sculpture, developed from his early studies and from his post-war questioning of societal and personal ethics.
Nagare's successes in the United States and in Japan began with his one-man show in Tokyo at the Yoseido Gallery in 1958 which attracted the attention of Lincoln Kirstein of the New York City Ballet. Kirstein praised the artist's work to Blanchette Rockefeller who ultimately launched Nagare's career in America. Nagare lived half of each year in America from 1962 until 1975 and he showed at the Staempfli Gallery in New York from 1963 to 1989. His work may be seen in permanent installations at the plaza of the World Trade Center in lower Manhattan (Cloud Fortress, 1975), and at the Metropolitan Opera House at Lincoln Center (two Bachi, 1973). His record of exhibitions and commissions in the United States and in Japan is extensive.
Amongst his one-man exhibitions in Japan are those at the Seibu Museum in Tokyo in 1977, the Umeda Modern Art Museum in Osaka in 1978, the Edobori Gallery in Osaka in 1981, 1985, 1990 and 1994, and the Nichido Gallery in Tokyo 1988 and 1994. In 1974 he received the Japan Grand Prix of Arts. In the United States his work is included in many collections including those of the San Diego Museum of Art, the San Francisco Museum of Modern Art, the Museum of Modern Art in New York, and the Honolulu Academy of Art. In Japan his sculpture is in the collections of the Takamatasu City Museum of Art, the Ohara Museum of Art, and the National Museum of Art, Osaka. He is represented in many other museum, corporate, and private collections.