The Type 2 120 mm mortar was considered an effective mortar by the Imperial Japanese Army; however, its production only commenced during the latter half of WWII, and its overall service action was limited.

“The mortar examined was manufactured at Osaka Arsenal in 1943. This mortar is described by the Japanese as having an overall length of 152.1 centimetres (4 ft 11.9 in), and a bore length of 136.1 centimetres (4 ft 5.6 in).

The total weight of the weapon is reported to be 248.8 kilograms (549 lb), of which 80 kilograms (180 lb) represent the weight of the tube, 45 kilograms (99 lb) the bipod, and 94.3 kilograms (208 lb) the base plate.

The weapon allegedly can be fired by dropping the shell down the tube to strike a fixed firing pin, or it can be trigger fired. Elevation of the piece, accomplished by adjustment of the bipod legs, ranges from 800 to 1,422 mils; traverse, at a 45-degree elevation, is 180 mils and at 70 degrees 210 mils. Maximum range of the piece is reported to be 4,500 metres (4,900 yd).

The base plate is very heavy and is fitted with four carrying handles. The sight bracket fits the standard mortar sight. The barrel is heavily reinforced at the muzzle and has two raised ribs midway of the barrel, between which the barrel clamping collar is held. The firing mechanism is similar to that used on the Type 99, 81 mm short mortar.

After the weapon has been loaded, a plunger, which projects upward from the mortar breech, is struck with a mallet or similar instrument, thus camming out the firing pin and firing the mortar. A safety lock is fitted on this firing plunger.“

Information from Wikidedia