Here is an overview video by Paradise Hobby of the Maruyama MP-IX MP9 GBB SMG going over its improvements over the previous KMP9 model. Key upgrades detailed include an M4-compatible buttstock adapter, a redesigned safety and fire selector, and a significantly improved hop-up chamber. The rifle is packaged with a 45-round magazine and a proprietary short suppressor.

The most unique improvement is the blowback unit and nozzle, which are based on the VFC 18C pistol design, making internal parts more accessible for maintenance and replacement. They praise the convenient feature of storing the hop-up adjustment hex key inside the gun. They conclude that the MP-IX MP9 is highly recommended for its performance, thoughtful design, and overall value.