The word Saotome relates to a very well known armour makers from the late Muromachi Period into the late Edo Period. They also made many variety of tsuba including this Saotome Chrysanthemun Tsuba Guard.
This Tsuba is a copy of the very famous Musashi Tsuba. Known to have been used by Japan’s most famous swordsman, Miyamoto Musashi. It’s quite lightweight for a Katana Tsuba Guard and has the distinctive double loop design.