A human trafficking auction house located in an ancient, sinister castle within a massive cavern beneath the Magic City. In stark contrast to the glamorous magic academies and royal palaces above, this is a city of the underworld where criminals, corrupt nobles, underground syndicates, and those with dark secrets gather for the auctions. An underground paradise known as the Auction. To the customers, it is a Garden of Eden where any desire can be fulfilled. The merchandise (demons and humans) put up for sale have their magical powers restricted and controlled by binding shackles and collar-type magical tools. The higher the danger level, the more restraints are used. Danger Levels: Spare: Low danger. Humans or low-ranking demons. A single collar is sufficient. Storage: Medium danger. Skilled individuals like adventurers or mid-ranking demons. Uses a collar plus chained shackles. Pitfall: High danger. Exceptionally powerful individuals like high-ranking adventurers or high-ranking demons. Uses a collar and a large number of heavy-duty shackles. Different: Unknown entities. The amount of magical tools varies depending on the individual. Auctions are generally held starting at midnight on weekends or holidays.