This was the first native-designed Japanese submachinegun accepted for service. A simple blowback design, the weapon was heavily influenced by the 7.65mm Swiss Bergmann submachinegun that had been purchased in the late 1920s. In spite of the weapon being of particular use in jungle warfare, the Japanese military did not see the value of the submachinegun. Three designs were tested in the mid to late 1930s with the third design finally being adopted as the Type 100. Field testing of the Type 100 did not prove entirely satisfactory for the design and relatively few of this model were manufactured. A number of the final production were converted into the Paratrooper model. A noticeable characteristic of the Type 100 (1940) and the derivative Paratrooper model is the very large cylinder under the perforated barrel jacket. This is the bayonet mount which is derived in part by what was supplied to the Japanese on the Bergmann submachineguns they had purchased earlier.
