This iron tsuba is decorated with openwork family crests that are highlighted with brass inlay in a style that reached the height of its popularity at the end of the 16th century. When mounted between the sword’s blade and grip to protect the user’s hand, these crests would encircle the blade of the sword. This tsuba is part of a group of guards inscribed with the same name and honorary title, for which they are known as Yoshirō-tsuba (与四郎鐔). Differences in quality, signature style, and production time suggest that Koike Yoshirō Naomasa was the head of a Kyōto-based workshop which continued to make tsuba for a few decades into the 17th century.