This is an antique Japanese military sake cup, decorated with a star that's recessed into the glaze and the words (also recessed) "Korea Defense Commemoration" "78th Infantry". There's a maker's mark on the back. This is a Korean celadon cup - Japanese ceramics don't have this technique and it's very much a Korean product. Note how the words are not written on the cup itself, but is part of the glaze and is very slightly depressed. It's quite an unusual piece compared to your typical army sake cups.

Condition: Mint

Size: 2.75" across