Yasuyoshi was a son of Samoji who was a master swordsmith in Chikuzen Province (northwest of Fukuoka Prefecture) in 14th century.
This tanto (dagger) shows the style and techniques which were passed down from his father, Samoji, to Yasuyoshi.
As stated by a document of the Tachibana family, this sword had been handed down from the first Lord Muneshige to the second and third lords as a weapon. Subsequently, the third lord gave it to his son as a talisman, hoping the sword could protect him.