no Kami Fujiwara Masatsune was born at Nodo in Province, where he initially signed his work Kanetsune. He later entered the service of Fukushima Masanori, at which time he changed his name to Masatsune and relocated to Kiyosu in Owari. In the fifth month of Tensho 19 (1591) he received the honorary court title no Kami. Working alongside Hoki no Kami Nobutaka and Hida no Kami Ujifusa, he became a retained smith (kakae-ko) of the Owari Tokugawa house, and in later generations came to be counted among the "Three Makers of Owari" (Owari Sansaku). In Keicho 12 (1607) he retired and entrusted the name to the second generation; however, his son died suddenly soon thereafter, whereupon Masatsune returned to active work and resumed forging under the tonsured signature Masatsune Nyudo. He is recorded as still working as late as Genna 5 (1619), at the age of eighty-four.
Masatsune's forging typically shows with a flowing tendency toward , often with adhering and a somewhat blackish tone to the steel. His characteristic is a base mixed with and , exhibiting well-developed , with and appearing. He was particularly skilled at , and his finest display a tight with well attached. In his works, a tendency and angular elements within the recall traits of the tradition, including features reminiscent of style in the . His are uniformly of large size, often in , bearing with accompanying terminated in , and his signatures are consistently cut with a thick chisel placed toward the .
Among Masatsune's extant works, are by far the most numerous; next come and , while and are exceedingly rare. He especially excelled at and was particularly proficient in , and his are noted as being of high skill. His demonstrate mastery of the form, though examples of the very highest level are few. The has recognized that his workmanship is good, that his distinctive features are well manifested in both and , and that individual pieces display facets of his style in which "the forging is exceptionally fine and superior."