Nagasone Tsunahiro

Tsunahiro (綱広) was a swordsmith active in Odawara, Sagami Province (present-day Kanagawa Prefecture) during the late Muromachi period, working in the Late Soshu (Odawara Soshu) tradition. He was the son of Shimada Yoshisuke, initially signed his blades "Masahiro" (正広), and was commissioned by Hōjō Ujitsuna. According to tradition, Ujitsuna granted him the character "Tsuna" (綱), prompting him to change his name to Tsunahiro. The Tsunahiro family subsequently perpetuated this name through successive generations until the end of the Edo period. Building upon the forging techniques inherited from his father Shimada Yoshisuke, Tsunahiro crafted practical martial blades capable of meeting the demands of warfare under Hōjō patronage, thereby establishing the Late Soshu style as a rooted tradition in Odawara.

Tsunahiro's blades are characterized by the robust strength and practical utility befitting Late Soshu work. The steel displays well-tempered itame hada with pronounced grain definition and ji-nie, exhibiting the refined and moist surface quality typical of the Soshu tradition. The hamon consists primarily of gunome interspersed with notare patterns, rendered in bright nie-deki that imparts a bold and powerful impression. While possessing the hardy toughness required for actual combat during the Sengoku period, his blades retain the rich scenic qualities inherited from the Soshu tradition—a duality that exemplifies his artistry as a Late Soshu master.

Tsunahiro's signed blades bear either "Tsunahiro" (綱広) or "Soshu jū Tsunahiro" (相州住綱広) inscriptions, whose calligraphy conveys strength and unpretentious character. In uchigatana (long sword) form, his works combine practical proportions and thickness suited to warrior wear with visually compelling combinations of itame steel and gunome-notare hamon, embodying both the utilitarian demands of the Sengoku age and the aesthetic principles of the Soshu tradition.

The Tsunahiro family perpetuated this name across successive generations following the founder, transmitting the Late Soshu (Odawara Soshu) lineage through to the end of the Edo period. Established under Hōjō dominion in Odawara, this school supplied martial blades meeting the needs of the Kantō region during the Sengoku period, embodying the regional development of the Soshu tradition. Successive Tsunahiro smiths maintained the founder's stylistic approach while adapting their output to the demands of each successive era.

Today, Tsunahiro's works are preserved in sword museums and other institutions, valued as important materials for understanding the Late Soshu style and the sword culture of the Kantō region during the Sengoku period. In genealogical research of the Odawara Soshu lineage, Tsunahiro's presence is recognized as a key to elucidating the transmission and development of the Soshu tradition under Hōjō authority.