In the wake of the calamitous 'Hammer of Eden' disaster that claimed six billion lives and submerged 90% of the world, the New United Nations emerges to restore peace amidst the ruins. Keel resides in Yabitsu, a town thriving on the energy from a nuclear generator left by the catastrophe. Aoi, Keel's relative and the New United Nations' secretary general, envisions a harmonious world where nations unite across racial and religious divides post-crisis. Yet, her noble aspirations face resistance from entrenched national interests. Enter Gould, a military figure advocating for order through force. Leveraging the nuclear submarine Ulysses and a crew that includes Keel's brother Tean, Gould stages a coup, sparking a conflict against the New United Nations and destabilizing Yabitsu.