Army Armaments Badge
陸軍技能章
The inscription on the badge and the box reads 'Technical Skills Badge, Army Armaments
Administrative Headquarters and the Units under the same Command.'

There were at least two classes,
Kou [1st Class] and Otsu [2nd Class], both shown below.
You can see differences in the design elements.

I'm not really sure about this badge, but this HQ group was formed in October 1942. Before
this date, there were three groups concerned with weapons development, weapons storage,
and technical research. On October 15th, 1942, these three units were merged into one, and
the last phrase on the box and badge appears to refer to that merging.

The HQ Commander of this group reported directly to the Minister of the Army. There were
only three HQ Commanders of this group:

Osuda [Katsutsugu?]: From Showa 17 [1942] 10/15

Kimura Heitaro : From Showa 18 [1943] 3/11  

Suga [Naritsugu??]: From Showa 19 [1944] 8/3

This HQ group was disbanded on April 1, 1945.
Kou [1st Class]
Kou [1st Class]
Otsu [2nd Class]
Another Otsu [2nd Class] example
The inscription reveals this to be a participation
badge from the first competition, so the date is
probably 1942.

Also: '3rd Training Competition' so maybe there
were more than one competitions in one year.
'Graduation Record. Technical Division Cadet Taku [??]. The person
named to the right has completed the studies in the technical division of
the officer's academy. Showa 18 [1943] December 23. Army Armaments
Administrative Headquarters Commander Lieutenant General Kimura
Heitaro.'