M.A.S.K. members are specialized operatives and professional demon hunters working for the M.A.S.K. (Multinational Association for Supernatural Keeping) organization. These individuals are easily recognizable by the unique masks they wear. The organization has a variety of masks, including Theater, Ornithic, Abstract, Animal, Automaton, Gas Mask, Oni, Ghost, and Knight masks.

M.A.S.K. members are classified into ranks from 0 to 4, with Rank 4 representing the most skillful operatives. An essential requirement to become a M.A.S.K. member is being part of the Persona family. This legacy ensures that the burden and pain of being a demon hunter remain within their family, preventing outsiders from experiencing it.

While anyone can become a Rank 0 member, these individuals are typically assigned very safe missions. They are viewed as kind volunteers and are compensated with credits for their services.