The blade shows the metalworking methods of the Fukuoka Ichimonji school, where craftsmen marked swords with a single horizontal line instead of traditional signatures. This mark became the school’s hallmark, setting them apart from other sword makers of their era. On the front side of the blade, a reflection called utsuri is stretched diagonally from the bottom to the point, and the irregular sword marks called midare utsuri, are spread across on the blade.

According to Legend, the sword was originally dedicated at Nikko Gongen (Nikko Futarasan Shrine / Nikko Gongen). Hojo Soun (1432–1519), the founder of the Later Hojo clan and a key figure in the early Sengoku period who established control in Izu and Sagami from Odawara, formally obtained it from the shrine. It then became a treasured family sword of the Later Hojo, passed down through successive lords (Soun → Ujitsuna → Ujiyasu and onward to the fifth generation).

During the Siege of Odawara (1590) which was the defining battle that made Toyotomi Hideyoshi the unifier of Japan. Yoshitaka Kuroda, who is also known as Kanbei or Josui, joined this battle with only 300 soldiers to support Hideyoshi.

As the battle progressed into a long stalemate, the Hojo family was then having a long meeting to determine whether they should counter or surrender while surrounded by enemy forces. The historic meeting originated the phrase “Odawara Hyojo” (a meeting of Odawara), which refers to a meeting that doesn’t reach a conclusion after a long time.

Yoshitaka bravely entered Odawara Castle (Kanagawa Prefecture) and in a defining moment successfully convinced Hojo Ujimasa and Ujinao to surrender the castle to Hideyoshi. Ujinao gave the sword Nikko-Ichimonji to Yoshitaka as a sign of appreciation for his help in communicating with Hideyoshi. According to the Kuroda Kafu (History of Kuroda family) written by Kaibara Ekiken, the sword was given to Yoshitaka together with the Hojo Shirogai, a trumpet shell, and the Azuma Kagami, a history book.