Its primary role was that of a lightweight mortar for assault and airborne troops that could be quickly assembled or disassembled.

The legs of the bipod, made of tubular steel, are mounted on the elevating screw housing by a clevis joint.

This shaft must be struck a sharp blow with a mallet to drive it inward so as to force the firing pin against the primer of the propellant cartridge.

[5] The Type 99 mortar is fired by manually striking a trigger with a hammer or other heavy object.

Ammunition of all kinds was packed in wooden boxes with fillers to hold it in position, and only the most rudimentary protection against moisture was provided by tarring joints and knot holes and occasionally wrapping rounds in wax paper for additional waterproofing.

Now, however, the Japanese are utilizing metal and asphalt-impregnated paper linings for their ammunition containers, and consequently deterioration has been materially lessened.