The location is Tristan, an urban metropolis that appears to be an amalgamation of turn-of-the-20th-century Tokyo, San Francisco, and Victorian-era London.

Due to an invisible contaminant called the "malediction", or simply the "curse", people who use magic too often are at risk in transforming into "Demons", or horrific, malevolent abominations of nature that become immune to ordinary weapons.

Magic, utilized in a safe sense by the Bureau, has been used as a viable energy source by the civil service, industry, agriculture, medicine, and the military.

All of these magic users, even the ones with innocent and well-meaning intentions, are in danger of tapping into the dark side either accidentally or on purpose and themselves becoming bloodthirsty beasts due to accidents or sabotage by Oddman's agents.

These Sorcerist agents wear a suit of armor that resists the negative transforming effects of magic.

These suits are referred to as "Mold Armor", or more commonly a "straitjacket", due to the fact they constrain human beings in their natural form.