This is a very rare antique Japanese military sake cup, made of glass and there are three things inserted into the glass - a photo of a sailor, and two miniature flags. There are some words under the photo - "Portrait of Commander XX" - I can't quite make out the name itself, but this looks like a navy officer. The items are clearly put in and then sealed at the bottom with this metal cap that has a registered design number of 1733. This is a very unique cup.

Condition: The photo is somewhat faded. Otherwise mint condition. The frosting is on the inside of the cup.

Size: 2" across