With brains and brawn now united, the next phase of Senkuu's plan to uncover the mystery of the green light that petrified humanity is to travel to the other side of the Earth to investigate its origin. However, to do so, Senkuu must first construct a ship. Assisted by Tsukasa Shishiou's former subordinates, the ship's hull is quickly assembled, but one essential component is missing: a capable captain. During their search, Senkuu and his crew discover a petrified Ryuusui Nanami—the heir to the largest maritime conglomerate, renowned for his extensive knowledge of sailing vessels but for his disagreeable personality. Despite this, Senkuu takes the risk and revives Ryuusui. Upon realizing that property rights do not exist in this new civilization, Ryuusui becomes excited at the prospect of claiming everything for himself. But before he agrees to play a pivotal role in their upcoming voyage and command the vessel across the turbulent seas, he and Senkuu must locate the king of fuels to power the ship—oil.