“The round iron plate is pierced with an openwork design of a paulownia crest (kiri-mon), the surface details of which are carved in low relief. The design is repeated on the reverse. The edge is slightly raised and the rim has some iron bones.” – this citation from Japanese Swords and Sword Fittings from the Collection of Dr. Walter Ames Compton. Part I. Christie’s, New York, March 31, 1992. accurately describes this piece. The only difference is the size – my specimen is slightly larger and thiner. Compton’s №3 on page 11: 78 mm x 77 mm x 3.5 mm, while this one is 85.1 mm x 84.8 mm x 3.2 mm at seppa-dai and 2.8 mm at rim. Compton’s tsuba was attested by Sato Kanzan.
It’s hard to tell whether the kozuka and kogai hitsu-ana are original, as they both lack raised rim. I would expect them to be cut later. Now both are plugged with soft metal almost the same color as the plate. The plate has dark, almost black, color with brownish hue.
Kamakura-bori school. Muromachi period (ca. 1450).
Height: 85.1 mm, width: 84.8 mm, Thickness at seppa-dai: 3.2 mm, at rim 2.8 mm.
Weight: 79.1 g (light)