Ramunes IV falsely claims the title of Fourth Warrior Ramunes. Selected in boyhood to impersonate the true warrior, he serves as a temporary leader for followers awaiting the real Ramunes' discovery. This imposed identity defines his existence, which he embraces completely.

His cruelly sadistic nature starkly contrasts with the previous Ramunes III known to characters like Cacao and Parfait. Commanding the colossal spaceship Giga Genos, he unleashes destruction through orbital bombardments of populated worlds and the captivity of children. He justifies his brutality as necessary to unite the galaxy under his rule and avert catastrophe.

He exploits Cacao’s loyalty to the Ramunes lineage in an attempted sexual assault. He manipulates Electone, an android duplicate from a related series serving as his assistant and lover. His alliance with Don Vodka, a part-android integrated into Giga Genos, ends in betrayal when Ramunes IV discards him after the excavation of the ancient weapon Dark Knight.

Driven by ambition, he attempts to activate the Dark Knight. The mecha rejects him as an impostor, inflicting fatal injuries. Dying within its control room, he expresses disbelief that his lifelong identity could be false, having internalized the role utterly.

Following his death, Electone reactivates the Dark Knight briefly before destruction. The true Fourth Warrior Ramunes is later revealed as Lemon, a twelve-year-old girl rescued earlier by Cacao and Parfait.