Superb lacquered wood sake cup. The gold gilt pattern has a combat helmet and samurai sword. Also some cherry blossoms.
The characters on the reverse of the cup read 'China Incident Commemorative, 9th Transport'.
The samurai sword was a standard part of the IJA uniform, and swords have been part of the Japanese military culture for hundreds of years, so seeing swords on cups is no surprise.
Usually the same kind of sheathed sword is on cups, and, as you can see from the examples here, they invariably appear with a combat helmet. I'm sure exceptions exist but I have yet to find one.
Note that in each of the following photos the sword is only part of the design; it never appears more prominent than the other symbolic elements.
I think that the most of the swords depicted here, though meant to be general military symbols, are the traditional katana that 'were converted for field use by the addition of a suspension mount and leather scabbard cover.' (Fuller, 32)