Le Caine, son of Admiral Gresco, a high-ranking Gradosian Empire official, arrives on Earth after the initial invasion. Appointed Supreme Commander of the occupied planet, he enforces Gradosian rule with near-absolute authority, overseeing military operations and suppressing human resistance.

He staunchly believes in Gradosian ethnic and cultural superiority over humans, viewing Earth's population as inferior. This conviction fuels his ruthless governance, driving systematic efforts to eradicate Earth's cultural heritage, art, and literature to facilitate subjugation. Despite his arrogance and commitment to supremacy, he adheres to a personal code of nobility, refusing underhanded combat tactics and valuing direct confrontation.

His relationship with Julia Asuka, Eiji's sister, introduces complexity. After her arrest for treason due to opposing the invasion, Le Caine orders her execution. Yet, inexplicably drawn to her spiritual strength, he finds himself unable to carry out the sentence. This attraction creates internal conflict, though it doesn't diminish his loyalty to the Gradosian cause or alter his ruthless methods.

As the primary antagonist later in the story, Le Caine engages in a prolonged rivalry with Eiji. Their conflict culminates in a decisive battle where Le Caine confronts Eiji directly. During this clash, an ancient Gradosian artifact activates, unleashing a massive energy discharge. The aftermath leaves Le Caine's ultimate fate unresolved within the televised narrative.

The alternative ending in the OVA *Kokuin 2000* expands this final battle, adding scenes and a more detailed epilogue. Le Caine's character arc and motivations, however, remain consistent with the television series, emphasizing his embodiment of Gradosian authoritarianism and his ideological clash with the protagonists.