By 1944 the Americans were using M1 bazooka anti-tank rocket launchers in the Pacific Theater against the Japanese.

In response, the Japanese began development of the Type 4 rocket launcher.

When the Chinese reverse engineered the American M20 Super Bazooka in the Korean War to produce the Type 51 90 mm rocket launcher, they used the data of the experimental Type 4 AT rocket launcher left at the 52nd Military Arsenal in Shenyang.

The pistol grip and trigger mechanism were attached to the rear half of the launcher.

A cable ran from the trigger to the rear of the launcher where the hammer was located.