In a universe scattered with ancient alien civilizations, humanity stumbles upon the remnants of a long-gone race on Solo. This discovery leads to their first encounter with a living alien race, the aggressive Buff Clan. As chaos ensues, the Buff Clan attacks the colony to reclaim Karala Ajiba, daughter of their military leader. To escape the onslaught, Cosmo Yuki, Kasha Imhof, and Bes Jordan commandeer three trucks that merge into the colossal robot Ideon. With their settlement obliterated, the survivors seek refuge on the newly unearthed spaceship, the Solo Ship, aiming to outrun their alien pursuers and secure peace. Yet, the unyielding Buff Clan relentlessly chases them, refusing to relent in their pursuit.