Sometime in the past, the people of the country of Parts had found a way to become immortal, but only with elderly nobles. Five of these elders—Ballossum Pench, Gabriel Hammer, Jimchuck Spanner, Olsorro Slasher, and Leonard Drill—obtained immortality, and became known as the Motoruin sages. Eventually, they attempted to take over the Parts kingdom and start a new world order, collapsing the government and destroying parts of the country in the process. As their plans unfold, five children of one of these villages decide to battle the Motoruin using another new invention: the semi-automatic propelling engine, known as "Progear".
There are two pilots to choose from in Progear, Ring and Bolt.
- Ring pilots the Gambler, which is the slower of the two ships and features a wide shot type.
- Bolt pilots the Militant, which is the faster ship and features a focused shot type.
There are three gunners which can be selected, Chain, Nail, and Rivet.
- Chain pilots the Alpha, which has focused missiles and deals average damage.
- Nail pilots the Beta, which has a spread shot and deals heavy damage.
- Rivet pilots the Gamma, which shoots homing missiles but deals low damage.
Alternative costumes for the characters can be chosen by holding down the start button on the selection screen.
Pressing A+B to select the gunner instead of just A splits them into a secret 'one on top and one below' formation.