S&A Detective Agency is a jack-of-all-trades in Lags Town placed on the outskirts of Diver City. Shu used to be a hot-shot police detective and fought for justice. He stood up against state authority but lost everything he had as a consequence and drifted into this town. Now he lives an easy life with his right-hand man (Akira), two assistants (Manami and Ayaka) but feels empty inside. One day, an incident leads Shu to come across the mysterious heroine, Sara, who has no memory of her past. The unprecedented truth is about to be revealed as he investigates the incident, and it will provoke a crisis involving the entire Diver City… Can Shu and his buddies protect what they cherish? And what is the future of Diver City...?