Derek Wildstar, originally named Susumu Kodai in Japanese media, captains the space battleship Yamato (renamed Argo in English adaptations) during the Bolar Wars conflict. Set in 2205 after Earth's recovery from wars against Gamilas and the Comet Empire, this mission launches when a stray proton missile from a Galman Empire (reformed Gamilas) and Bolar Federation battle strikes the sun. The impact accelerates nuclear fusion, threatening solar system annihilation within one year. Commanding the Yamato, Wildstar simultaneously pursues a new homeworld for humanity and a solution to restore the sun. His leadership demands navigating interstellar politics, sustaining crew morale, and executing strategic decisions against unrelenting time pressure.

Mid-mission, Wildstar encounters Desslok, former Gamilas leader now governing the Galman Empire. Expressing remorse for Earth's involvement, Desslok forms a temporary alliance with the Yamato. Wildstar manages this fragile partnership while confronting the hostile Bolar Federation, which targets Earth over its Galman ties. The alliance strains when the Yamato rescues Ruda (Princess Mariposa in English adaptations), exiled queen of the hidden planet Shalbart. Revered by peace factions across Galman and Bolar societies, Ruda faces elimination from both governments. Wildstar grants her sanctuary aboard the Yamato, prioritizing her protection despite diplomatic risks to Earth's precarious position.

Wildstar's command confronts intense tactical challenges: direct combat with Bolar forces, intricate interstellar alliances, and strained crew dynamics under prolonged duress. The mission culminates at Shalbart, where Ruda supplies the Yamato with the Hydro-Cosmogen Gun—a device capable of stabilizing the sun's fusion. Successful deployment requires crew sacrifices and Wildstar's decisive action to ensure Earth's survival. This resolution reinforces his commitment to humanity's protection and cements his legacy as a pivotal figure in Earth's interstellar history.