Mercury has red long hair tied into a ponytail with a white ribbon and has an "X" shaped white hair clip on her left bangs. She has sky blue eyes. She wears a white long coat with black cuffs and black belt. Underneath her coat is a black dress shirt and red tie. Behind her coat is a red ribbon. She wears black and white pinstriped stockings/leggings and knee length white boots which have one wing each on the rim. She has a visible golden halo above her head and 3 pairs of small, detailed wings. She also wears white gloves and she has rectangular goggles resting on her shoulders.
Not much is known about her.
Not much is known about her past.
Up to this day, Mercury has only appeared in some of Deep-Sea Prisoner's Illustrations.
Elux is Mercury's boss.
Sol is Mercury's comrade.
Luna is Mercury's comrade.
Mars is Mercury's comrade.
Prior to becoming a devil, Reficul was a comrade of Mercury.
- Her name is probably based from the planet Mercury. 
- The name, Mercury is also a periodic element, Hg, with an atomic number of 80. It commonly known as quicksilver.