Although lacking the necessary expertise for his Metropolitan Police Department investigative team role, Totomaru Isshiki remains resolute in his pursuit of solving murders and assisting those in need. Following a senior officer's guidance, Totomaru seeks the aid of the reclusive Ron Kamonohashi, a former top student at the prestigious Detective Training Academy Blue who has since retired from public life. Expecting a poised and collected individual, Totomaru is taken aback by Ron's disheveled appearance and eccentric behavior. Disconnected from society for years, Ron is vastly different from the person he once was and initially declines to assist the officer. However, Ron has a change of heart and dives into the ongoing serial murder probe with unbridled zeal. Ron's departure from the world of detective work did not stem from a lack of interest, but rather from circumstances beyond his control. Totomaru may hold the key to Ron's return to the field of investigation. Together, the optimistic but unseasoned officer and the unpredictable detective take on every new mystery with eagerness.