A fierce storm of mysterious origin engulfs a fleet of ship girls at sea, and when the chaos subsides, Zuikaku, Eugen, and several of their companions find themselves shipwrecked on the shores of a deserted island. This parallel story diverges from the main timeline of the anime, thrusting these former allies from the Crimson Axis into an unexpected and precarious situation. Their first discovery on the island is not rescue, but their enemies: the KAN-SEN of the Azur Lane alliance. Stranded together with no immediate hope of escape, the hostile factions are forced into an uneasy ceasefire, agreeing to set aside their ideological war to focus on the more immediate threat of survival on the uninhabited island.

The heart of the narrative follows the makeshift community they build around an abandoned school discovered deeper inland, which becomes their central base of operations. Leaders emerge from the two rival camps to guide the group: Zuikaku, the proud carrier of the Sakura Empire, and Eugen, the cunning heavy cruiser of Iron Blood. Their contrasting personalities and leadership styles create a dynamic tension, yet they must cooperate to manage resources, explore the island, and maintain morale. As the days pass, more ship girls from all factions, including the Union and the Royal Navy, appear on the island, each bringing their own skills and quirks to the survival effort. The forced proximity gradually breaks down barriers, transforming former enemies into reluctant comrades and eventually close friends as they share meals, build shelters, and navigate the humorous and hazardous challenges of island life.

The deserted island survival scenario forms the main narrative arc, shifting the focus from large-scale naval battles to personal interactions and collective problem-solving. The story explores how characters defined by their allegiances begin to see each other as individuals beyond their factions. As the series progresses, the initial mystery of the storm and the island itself deepens, hinting that their stranding may not have been an accident. The plot builds toward an emotional climax where the bonds forged during their time together are tested, forcing the ship girls to confront the possibility of returning to their former conflict and what it means to have found unity in isolation. The final volumes bring this survival story to a grand conclusion, resolving the mysteries of the island and the fate of its unlikely inhabitants.