The PM-9 was developed to fulfill the requirement for a new submachine gun in JSDF service. It was adopted for non-frontline proposes, such as a backup weapon for vehicle operators, and special operation units in 1999. It remains in limited service with Japanese military and police special forces.
The PM-9 is a blowback-operated submachine gun based on the Uzi, using the same action. It features an integral foregrip to aid in sustained fully-automatic fire, a flash suppressor is also placed at the end of the barrel. The weapon can be upgraded with optional attachments, such as a folding stock, a sound suppressor, and a reflector sight. Pre-production models of the PM-9 used wooden furniture.