The province of Yamashiro (present-day Kyoto) has been a major production center of swords since ancient times, with many historically prominent swordsmiths hailing from there. Emerging as the pinnacle of Yamashiro sword-smithing is the Rai school, which was active from the mid-Kamakura to the Nanboku-chō period (13th–14th century). This school produced many skilled smiths, the most prolific of whom was Rai Kunimitsu, who had created this tachi. According to the Kanchi’in Temple version of the Meizukushi (All About Swords), which was transcribed in the Muromachi period (14th–16th century), the Rai school’s lineage of swordsmiths originally came from the Korean kingdom of Goryeo. Given how swords are taken to symbolize Japan’s unique military and aesthetic culture, it is interesting how there are sources claiming that the most prolific Rai school of sword-making had descended from foreign immigrants, even if we have no way of ascertaining the truth in that statement.
The sword itself features a beautifully fine grain and a wide, straight sword blade pattern (suguha). The blade itself is wide, and its tang remains long even after having been shortened before. The way the blade curves dramatically from around its center to its tip gives it a dynamic, mesmerizing regality.
This sword was passed down in the Matsudaira family, after allegedly having been used by Matsudaira Tadaaki (1583–1644) in the Siege of Osaka (1614–15). It later passed through the hands of the Iwasaki family in Mitsubishi, former prime minister Yamagata Aritomo, Emperor Meiji, then Tokyo National Museum. Eventually, ownership was transferred to Kyushu National Museum after its opening in 2005.