Regiment collar tabs (used on
uniforms up until 1938)
Imperial Japanese Army Colors of Individual Service Branches

Collar Badges: the color identified the service branch.  Those serving with infantry, cavalry, field artillery,
etc. merely wore regimental numbers.

Chevrons: small zigzag worn by all ranks above the right breast pocket in the arm of service color.

Colors of the various service branches:

Black                           Military Police (Kempeitai)

Green                           Cavalry

Red                              Infantry and Tanks

Pink                             Intendance Department

Yellow                         Artillery

Dark Green                  Medical Department

Burgundy                      Engineers

Purple                          Veterinary Department

Dark Blue                     Transport

White Dots on Red       Military Band

Blue                             Army Air

White                           Judicial Department


Thanks to Rich for this fantastic info about the collar tabs!
Actual collar tab
Inscribed on reverse: '9th Infantry, Terada.'
Unpainted collar tab, which would lead one to
believe that it is a white judicial tab. However, it is
inscribed: 'Heavy Transport, Baba.'
Inscribed 'Discharge Commemorative' and on
the reverse 'Engineer 16th Division, Uetsuji.'
Nice fluted design.
Here are two engineer cups
with regiment collar tabs, both
3rd Regiment.
Inscribed '16th Transport,
Discharge Commemorative'.
Inscribed '16th Engineer Unit,
Stationed in Manchuria, Discharge
Commemorative.'
Most collar tab cups have the regiment number,
but this one has the artillery unit insignia.
Inscribed 'Yokohama Artillery, Discharge
Commemorative'.
Inscribed 'Transport Infantry,
Furlough Commemorative'.
A horse carrying a regiment collar tab in his mouth. Inscribed 'Transport
Infantry 3rd Division, Discharge Commemorative, Ito'.
Navy engineer cup with the regiment collar tab over an anchor.
Inscribed '3rd Engineer, Discharge Commemorative, Shibutani'.