During the late 21st century, humanity faced a brutal onslaught from extraterrestrials that materialized abruptly through wormholes. The people were powerless to repel the invaders and accepted their impending doom. In that same period, a supreme weapon capable of manifesting objects from imagination was uncovered inside a vast cavern beneath Japan, together with its youthful guardian Ryuusei who lay in cryogenic suspension. The relentless alien bombardment awakened him, and he guided the survivors to a conclusive triumph.
A year later, as the zones scarred by the alien assault were still under reconstruction, Ryuusei was named commander of Earth"s newly established Defence Force, tasked with countering interstellar threats. Yet he alone possessed the ability to operate the "imagination embodiment device." Any harm to him would doom the planet. Consequently, the Defence Force recruited capable women to serve beside him. Though initially reluctant, each had personal motives for joining Ryuusei"s cause. Consequently, the elite unit "Blade Briders" was created to defend Earth against the returning extraterrestrials.