As we know, there are many simularities between Owari, Kyo Sukashi and Ko Shôami tsuba. In this instance the maru mimi preculdes this from owari work and the large tekkotsu are not common on Kyo sukashi so this tsuba falls into the Shôami group. Edô period Shôami tsuba would not have large tekkotsu like this.
The theme is described as Sanbon Kasa no Zu 三本傘の図. 3 parasols (umbrellas are arranged with a central Kasa open, showing the framework underneath and 2 more, one on each side that are well carved in Niku bori 肉彫. The umbrellas from the front look quite round but the sukashi walls are square and flat. On the outer side of these Kasa are single gourds, connecting the sukashi to the mimi.
NBTHK Hozon – 日本美術刀剣保存協会の保存刀装具鑑定書.
The dimensions are 72mm x 71mm x 4mm
The design of Sanbon Gasa could be related to the family crest (Kamon 家紋) known as Itowa ni Nakabiraki Sanbongasa 糸輪に中開き三本傘。
I am still researching this family and will add more as I come across it.
Thank you for reading.