Marcus, who is bad at communicating with others and shy by nature, unexpectedly becomes the head of the Arcane Incident Department through a mix-up. Faced with eccentric, erratic coworkers like Regulus and Medicine Pocket, can Marcus—who used to get nervous even raising her voice—rise to the occasion in a crisis and become the anchor that holds this strange team together? —Are these seemingly odd people... really as "unreliable" as they seem?