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.
If you can read Japanese, there's an interesting webpage about this Armaments Unit HERE.
The HQ Commander of this group reported directly to the Minister of the Army. There were only three HQ Commanders of this group: