The golden ring of the Nibelung, forged from the Rhine gold, grants its bearer the absolute power to rule the universe, but only to one who first renounces love forever. This cursed artifact drives the conflict across two distinct manga adaptations of Richard Wagner's epic opera cycle, Der Ring des Nibelungen.

In Leiji Matsumoto's science fiction reimagining, the story is transposed into a space opera featuring characters from his broader universe, such as Captain Harlock and Tochiro Oyama. The narrative follows the four-part structure of the original operas. It begins with Das Rheingold, where Alberich, the leader of the Nibelung, steals the gold of the planet Rhine and forges the ring. As Alberich uses its power to invade Valhalla, Harlock and Tochiro, warned by the Nibelung woman Mime, head there aboard their ship, the Arcadia. In Valkyrie, the god Wotan, who possesses power beyond time, sends his nine Valkyrie daughters to eliminate Harlock and Tochiro in the past. The timeline shifts to the year 2964 AD, where Earth has lost the First Interstellar War and is ruled by Wotan. Great Harlock and Dr. Oyama flee Earth on the spaceship Death Shadow No. 1, encountering figures like the Metanoid warrior Helmazaria and the Valkyrie eldest daughter Brunnhilde. Meanwhile, the young Harlock and Tochiro meet the sisters Emeraldas and Maetel aboard the spaceship 999. The third part, Siegfried, focuses on Great Harlock and Dr. Oyama as they fight to protect the universe from the Dark Queen's invasion, with Brunnhilde defying her father Wotan to aid them. The saga concludes with Gotterdammerung, the Twilight of the Gods. A decade after his father's death, Captain Harlock learns the truth of these events from Mime. Seeking revenge against Wotan and Valhalla, he and Emeraldas go to battle. Wotan's attempts to alter the past trigger a cataclysm that threatens to destroy Valhalla itself.

Another manga adaptation of the Ring of the Nibelung, created by Riyoko Ikeda and Erika Miyamoto, follows the original Norse saga and Wagner's operas more faithfully. The story centers on the hero Siegfried. Raised in the woods by the blacksmith Mime, he is accustomed to a harsh life of fighting. His destined journey begins when Mime is killed by a soldier, sending Siegfried on a quest for revenge. Along the way, he meets the god of thunder, Wotan, and his daughter, the warrior maiden Brunnhilde, with whom he falls in love. The cursed ring, guarded by the Rhine maidens, changes hands from the dwarf Alberich to the gods to the giants, bringing ruin to all who possess it until it is finally returned to the river.