Imari-ware soba choko (soba noodle dipping cup) of uncertain age-- present condition, interior kiln mark and base design suggests appx ~100 years old, late Meiji or early Taisho period. Porcelain with underglaze cobalt blue painting of a classic arrowhead pattern. H. ~2" x Dia.~3".
Soba choko were originally used for small morsels of food much like the mukozuke or ko-zara are used in today's Japanese place setting. It was not until later in the Edo Period that they were made specifically for use as noodle dipping cups, as soba noodles became a popular urban dish by the 1800s. Their role later shifted to use as casual tea and sake cups.
They can still be used to elegantly serve soba or somen noodles, food as a mukozuke dish food or any small food serving, and they are also excellent for sake, of course!
Similar cups are listed on eBay for $60-200, but as I lack the expertise to affirmatively identify this piece, its price is deeply discounted.
