Rinne (燐子, Servants, lit. "light-bearing child") are beings who act as servants for certain Crimson Denizens. They are created when a Denizen blows Power of Existence into an object of this world. Rinne are unstable existences and require a constant replenishment of Power of Existence from their master. They can consume humans and give the Power of Existence they had gathered to their master, who can convert it for their usage in order to survive. They usually possess the same color of Flame as the Denizen who created them. Without their master, they will disappear because they are unable to convert the Power of Existence for their own usage. As noted by Shana when she is incarcerated in the Seireiden and stripped of her powers, though the Rinne are usually weak enough to be easily dealt with by Flame Haze, they are still powerful enough to easily dispose of normal humans.
Rinne of the Autonomous Type (自律タイプ Jiritsu Taipu ) are able to think for themselves and act independently.
The Rinne of the Autonomous Type that have been seen over the course of the series are:
- Marianne, Nina, Lauretta, other names unknown: Created by Friagne
- Domino: Created by Dantalion
- A stray Rinne (はぐれ燐子) with unknown name who wandered into Misaki City (first season anime original): Creator is unknown.
- Maids of unknown name, Shana's minders at Seireiden: Creator is unknown, administered by Bal Masqué
- Giant Ant Lion type (third season anime original): Creator is unknown
Rinne of the Tool Type (道具タイプ Dōgu Taipu ) are incapable of doing anything unless programmed or ordered to by their creators or current users.
The Rinne of the Tool Type that have been seen over the course of the series are:
- Pinion: Created by Tiriel
- Aeria: Created by Merihim
- Ukobach's aid (semi-autonomous when ordered): Created by Ukobach
- Four-way Ghosts: Created by Gaap
- Moddey: Created by Doog
- Taijinkunshi-gō, Onjūtonkō-gō, Kujinkanrai-gō, and Mujōjinsoku-gō: Created by Para
- Centipede type: Created by Ōnamuchi
- Cannon type: Created by various Bal Masqué Denizens
- Improved Cannon type: Created by various Bal Masqué Denizens, Haborym's army
- Plant type: Possibly created by Bel Peol
- Sabrac's scapegoat: Created by Bel Peol
- Camel type: Created by Paimon