Sterling Silver Miniature Shamisen

These appear to be a set of salt & pepper shakers in sterling silver 925. Measure about 4" long each and have a slide door on the back and holes in the side. One set of holes is slightly smaller than the other. Well made and fine detail to make them look like miniature shamisens. Came in a wooden box. These were found when cleaning out my Grandmother's house. My Grandfather was a Navy chaplain during WWl and was given many gifts in form of payment for his services when stationed in Japan. I've never seen any of these before and would like to find out age if possible.