MACHINE GUN UNITS
The kanji for Machine Gun Unit are above. It is difficult to tell
whether a cup belonged to a member of a Machine Gun Unit
because sometimes these gun designs were used generically.
However, machine gun units were included in different regiments,
and sometimes this specialization wasn't noted on cups.

And once in a while you will only see the kanji, no machine gun
picture.
A bit hard to read--handwritten in a leisurely
script. Read from right to
left:KI-KAN-TO-TAI. Sometimes you will see
just the first character (KI), usually
following the regiment number.
Marked 'Korea, 73rd Regiment, Machine
Gun Unit.'
Marked '6th Infantry Northern Manchuria.'
This one reads, from left to right, KI-KAN-TO-HAN. The last
character, HAN, means group or unit. The other two
examples I've included use a different kanji at the end. (TAI
meaning regiment)
This one reads, from left to right, KI-KAN.
Nice FUKIZUMI (blown ink) flowers. Marked
'40th Regiment, Machine Gun Unit.'
Marked '10th Infantry, Machine Gun Unit.'
Marked '19th Infantry, Machine Gun Unit.'
Marked '33rd Infantry'
Marked '4th Infantry'
Marked '18th
Infantry.'
The following cups are marked Machine Gun Units. The detailed gun
is a hint that these are not just general war symbols.
Cup from Shanghai. The characters read 'Shanghai Dispatch,
Victorious Return Commemorative, 19th Infantry, Light Machine
Gun Unit'.  
Marked '31st Infantry'