As Senkuu and his allies combine intellect and strength, their next move involves investigating the origin of the mysterious green light that petrified humanity by voyaging to the opposite side of the world. To accomplish this daunting task, Senkuu sets out to construct a ship, with the assistance of Tsukasa Shishiou's former followers who swiftly lay the ship's foundation. However, the final piece of the puzzle—a capable captain—is missing. In their quest, they stumble upon a petrified Ryuusui Nanami, the heir to a prominent maritime empire renowned for his sailing expertise but infamous for his disagreeable demeanor. Despite Ryuusui's self-serving tendencies in this new world without ownership boundaries, Senkuu decides to revive him, banking on his skills. Eager to seize control of the resources in this nascent society, Ryuusui sees an opportunity. Yet, before he commits to leading the expedition and steering the vessel across treacherous waters, Senkuu and his crew must secure a vital resource—the king of fuels: oil.