See Juyo token to zufu, vol. 12/2, no. 104, for an identical blade.
Credited as being the founder of the Owari shinto tradition, Masatsune I was born in Nando, Mino Province and belonged to the school of Nara Taro Kanetsune. The son of Seki Kanetsune VII, he was first called Nando Sasuke and later, Taro-no-suke. At the beginning of his working career, he used the name Kanetsune. In 1567, he moved to Komakimura, Owari, where he worked for Oda Nobunaga. Moving later to Kiyosu within the same province, he produced blades for the daimyo Fukushima Masanori. He received the honorific title of Sagami (no) Kami in 1591 and changed his name to Masatsune after having been given the right to use the "masa" from Masanori's name, although he slightly changed the way it was written. Masanori was transferred to Hiroshima in 1600 and Satsuma-no-Kami Tadayoshi, son of Tokugawa Ieyasu, became lord of Kiyosu and took Masatsune into his service. In 1610, three years after his retirement, Masatsune made his final move, to Nagoya, where he established a permanent residence. The succeeding seven generations of Masatsune smiths served as family retainers to the Bishu clan. In the Keicho 12 (1607), Masatsune retired and added the title Nyudo which he used for the following twelve years until his death in Genwa 5 (1619) at the age of 84.
See lot 243 in this sale for another reference to Fukushima Masanori.
During the period in which he used the Kanetsune name, he adhered closely to the traditions of the Seki school, specializing in suguba and gonome midare. After assuming the Masatsune name, he eventually developed his mastery of fine jitetsu; the majority of his mature works, such as this example, display either an elegant suguba, gonome or notare on a densely compacted hada.