Proto Max Jr. (MA-5) is one of the Proto-Max Units. He first is seen attacking Birdy and Bomber Zero. He fights Daibon, but when the Jetters retreated, he had to deal with Musashi as well. He is later seen along with Heavy Max to keep Jetters from stopping the arms. He is defeated by Ninja Bomber and Bomber The Kid. He is later summoned by MechaDoc to form Dark Force Bomber. After Dark Force Bomber's downfall, Proto Max Jr. is destroyed for good.
- Slingshot - Proto Max Jr. can shoot bombs from his slingshot.