Marie is a dominatrix who wears a gown and lives in a large European-looking house full of torture devices. Her husband and 'pet', Pochi, is a gigantic man wielding an axe who does everything she asks him to.
She manages to trick Mikagami into drinking from a drugged teacup, and eventually straps him to a statue with the intention to make him her new 'pet'. She attempts to drug Domon, but because he drank from the same spot on the cup that Marie drank from (that was the only part that wasn't poisoned, though that was only because he wanted an 'indirect kiss'.), Marie's plan did not work. She commands Pochi to attack Domon, and she intervenes when Pochi begins to get overwhelmed. Recca arrives, and he and Domon manage to defeat Pochi and Marie. Mikagami straps her to the statue after she is defeated.
She is freed by Team Kū member Fujimaru, and tricks him into becoming her new 'pet', naming him 'Mogu'. Eventually, she, Pochi, and Fujimaru leave SODOM, although Marie's whereabouts are unknown. Pochi was listed to face off against Saicho in the next Ura Butou Satsujin, so Marie was likely nearby, and Fujimaru was seen with Kukai and Tatsuko.
She's skilled with poisons and drugs as she drugged Mikagami with something on her teacup.
She wields the madōgu Sokubaku Benten (Goddess of Binding): An elongating cat-o'-nine-tails that can extend and grip opponents, and will tighten even more when the opponent struggles. She lost it to Recca.