Nanakusa (Ryusei Yokohama) and Yuu Manabe (Marie Iitoyo), childhood friends who drifted apart, unexpectedly reunite on Kaiden Island, a place known for housing society's abandoned souls. As they rekindle their friendship, they become entangled in mysterious cases unique to this isolated location. Together, they embark on a quest to uncover the island's secrets, navigating through an enigmatic landscape of lost and forgotten individuals. Their investigation leads them deeper into the island's dark mysteries, challenging their understanding of connection and survival. Will their shared history and determination help them unravel the truth, or will they discover something far more unexpected? Based on the novel "Inakunare Gunjo" by Yutaka Kono, this is a 2019 Japanese sci-fi adventure mystery film directed by Akina Yanagi.