Very rare naval cup made for a
bugler.  The characters say,
'Yokosuka Naval Barracks, Bugler
Corps, Discharge Commemorative.'
The inscription from the cup above. Bugler Corps.
(Shou-Shin-Gou-Hei)
Note that this term was for a bugler who gave signal on board ship
MILITARY MUSIC CUPS
Cups specifically labeled 'Bugler' or 'Military Band' are quite rare. I have only run into
a few examples. Sometimes you may find cups with a bugle on them, but usually
these are not inscribed with anything other than a regiment number.  I suspect that
they have some connection with buglers, though there is no way to prove that.
The characters say, 'Military Band Unit, Discharge
Commemorative.' Some kind of harp or lyre symbol
that resembles the collar insignia (see an example to
the left) of military band units.
From the top: GUN-GAKU-TAI
(Military Band Unit)
Here are some cups with bugles on them.
None of them are inscribed with anything
that connects them to buglers, though.
Inscribed with a personal name: 'Ishii [?]'
Inscribed '34th Infantry'. Thanks for the photo, Steve!
The characters say, 'Infantry 33rd Regiment, Furlough
Commemorative.'
Bugle at the bottom. The characters say, 'Infantry 58th Regiment Commemorative.'
Rice bowl with a bugler and battle flag on either side. It is very
hard to find buglers on any kind of WW2 item.  
A scarce cup with a bugle in the design.

Inscribed '68th Infantry, Furlough Commemorative'. I cannot read the
poem in the center.

Inscribed 'Transport Unit, 4th Division, Discharge Commemorative'.
There is a bugle in the design. Inscribed 'Disbandment Commemorative,
9th Infantry, 8th [Division?], Murai.'
The insignia at the bottom is almost certainly the Military Band Unit
emblem.
Inscribed 'Commemorative' and then a 3-line poem or slogan. After that,
there is a phrase 'kikubi yori' which means 'An ideal day for a
chrysanthemum,' and a phrase that may mean '[marching?] ceremony.'
The chrysanthemum is the Imperial flower.
The kanji I translated as marching is shuu, which really means circuit, lap,
or going around.