The second installment of Kidou Senshi Gundam Thunderbolt picks up seven months post the One Year War. The remnants of the Principality of Zeon rebrand themselves as the Republic of Zeon and persistently fight on. At the "Thunderbolt Sector," where the Moore Brotherhood's fleet was decimated, Daryl was at the helm of the mobile suit Psycho Zaku in the final stages of the war. After the loss of Psycho Zaku, Daryl lands on Earth and transitions into the role of an intelligence agent. His aim is to gather insider knowledge on the South Seas Alliance, a faction within the Earth Federation. Meanwhile, Io, who had encountered Daryl in combat, is chosen to pilot the prototype mobile suit Atlas Gundam and embarks on a journey toward Earth.