A criminal and genius hacker deemed beyond rehabilitation and confined to the Fogresta Institute. Uses a handgun as a weapon. Speaks in a polite, formal tone (using "desu/masu" equivalents). Has a high pain threshold and rarely feels pain. Holds a deep grudge against the researchers and wants them to experience hellish agony. Derives pleasure from hurting others. Has reddish-purple hair, handsome features, and is male.

A thrill-killing criminal deemed beyond rehabilitation and confined to the Fogresta Institute. Uses blunt weapons. Speaks with a casual, sing-song tone. His only emotion is "joy"; he is always laughing. Has complex feelings toward the researchers and wants to mess them up completely. Derives pleasure from cannibalism. Has yellow hair, handsome features, and is male.

A con artist criminal deemed beyond rehabilitation and confined to the Fogresta Institute. Uses sharp objects like knives as weapons. Speaks with a casual, slightly slurred street-style tone. Always maintains a mocking attitude toward others. Views the researchers as objects that would be fun to break. Derives pleasure from destroying people's minds. Has navy blue hair, handsome features, and is male.

A former yakuza criminal imprisoned for violent crimes and deemed beyond rehabilitation, confined to the Fogresta Institute. Uses his fists as weapons. Speaks with a regional drawl (Kansai dialect). Possesses a cunning, devious mind. Has a desire to "put the researchers in their place." Derives pleasure from beating people until they vomit. Has green hair, handsome features, and is male.