Renton spends the entire movie trying to save Eureka, only to discover that saving her means losing her forever. The romance isn't a subplot here, it's the thing that breaks him, that drives every choice, that makes the ending unbearable. A kid who swore he'd rescue the girl he loved learns that some promises cost you the person you're trying to save.

Renton and Eureka grow up inseparable as small children. She cannot survive in sunlight. But one day she is taken away, and Renton, powerless to stop it, vows to rescue her. Years later, humanity's war against the Image, a mysterious life form from space, has lasted half a century. Renton joins the military, and his exceptional performance with the Nirvash, a bio-mechanical armor, earns him a place in the 303rd unit aboard the mother ship Gekko under Holland Novak. Unknown to him, a plot to end the alien invasion involves both him and Eureka. Torn between duty and emotion, the pair face trial after trial, and as the final battle nears, their choices may decide humanity's fate. The film blends mecha action, science fiction and romance.