Seikuu-O is the third of Engine Sentai Go-onger's already generous roster of giant robots, and it belongs to the Go-on Wings – Go-on Gold (Hiroto Sutou) and Go-on Silver (Miu Sutou). Unlike the ground-bound Engine-O, Seikuu-O is a pure aerial combination, formed from the three sky-faring Engines Toripter, Jetras and Jum-bowhale. Its name is a play on words meaning roughly "sky-punching king of the heavens." In Power Rangers RPM it appears as the Mach Megazord.

In its default configuration, Engine Toripter (a helicopter) serves as the right arm and Engine Jetras (a jet) as the left, while the massive Jum-bowhale – half jumbo jet, half whale – forms the torso and legs. Its helmet is styled after a jet pilot wearing an oxygen mask. Thanks to its slim frame, Seikuu-O is exceptionally agile both on the ground and in the air, dodging projectiles with ease. It wields the Toripter Rotor, whose blades double as a spinning shield, and the Jetras Bow. For its finisher, the Seikuu Impulse, a blue arrow extends from Jum-bowhale's mouth, is drawn back between Jetras' wings like a bowstring and loosed into the target with tremendous force.

As a DX toy, Seikuu-O was released by Bandai (Japan) via the separately sold Engines No. 7, 8 and 9, each packaged with its own "Engine Soul" – the little plug-in figures that slot into the cockpits and trigger Go-onger's signature Soul mechanic. The combination is "activated" through the Grip Wing Trigger and the 7-8-9 number code. Gimmicks include Toripter's free-spinning rotor blades, a firing missile in Jetras, and Jum-bowhale's fold-out wings, whose sheer size is genuinely impressive for the largely ABS-plastic DX line. Among collectors, Seikuu-O is regarded as the daintiest and lightest of the four Go-onger mecha, but it wins fans over precisely with its unique flight-based design.

Like all Go-onger Engines, this trio is expandable: together with Engine-O, Toripter, Jetras and Jum-bowhale form Engine-O G9 (the SkyRev Megazord in RPM), and they ultimately fold into the ultimate twelve-Engine combination, Engine-O G12 (the RPM Ultrazord) – a must for any complete Go-onger display shelf.