Overview
This short sword (tantō) was crafted by Nagashige, a master smith from Bizen-Osafune, representing the Nambokuchō Period (1336–1392). Nagashige is known as a pioneering artisan who blended the traditional techniques of Bizen with those from Sōshū. This sword is considered one of his greatest masterpieces. The inscription “Kōju” refers to 1334 CE, making it an exceptionally valuable historical document because its creation year is clearly identifiable. It was historically passed down through the Mitsui family.
Historical Background
The Nambokuchō Period was a time of great turmoil, following the collapse of the Kamakura Shogunate and leading to conflict between two rival courts (the Northern and Southern Courts). During this era, Japanese sword styles changed significantly. They became larger and more imposing in appearance due to shifts in battlefield tactics. Nagashige is believed to have branched off from the mainstream Bizen-Osafune school, establishing a dramatic style that featured strong nie (crystalline patterns) unlike previous Bizen swords. The year 1334, when this sword was made, coincided with the beginning of Emperor Go-Daigo’s Kenmu Restoration. This powerful energy and strength from a period of profound transition are evident in the blade itself.
Features and Appeal
This tantō is a concentration of Nagashige’s superior craftsmanship and the unique characteristics of the Nambokuchō Period.
- Imposing Appearance: The sword has a wide body, reflecting the preferences of samurai during that time. It exhibits a structure typical of the Nambokuchō Period: thin layering and an extended blade tip.
- The Zenith of Sōden-Bizen: It masterfully fuses the brilliant chōji midare (decorative wave pattern) unique to Bizen swords with the dramatic working patterns, such as jini-e (fine crystalline patterns) and kin-suji (gold lines), found in Sōshū techniques. This combination achieves extremely high artistic completion.
- Valuable Date Inscription: The “Kōju” inscription etched on the back is a crucial clue for dating its creation, making it an essential benchmark piece for understanding Nagashige’s active period and stylistic evolution.
- Beauty of the Core Steel: The forging shows prominent itame-hada (wood grain texture) and finely detailed chikei (ground patterns), allowing appreciation of beautiful core steel that is both refined and varied. Furthermore, the fact that it has three distinct ridges (mitsu-mune) enhances the sword’s inherent dignity.
Source: Excerpted from the National Designated Cultural Properties Database (https://kunishitei.bunka.go.jp/bsys/index)