Frey is a former member of the Ten Great Demon Lords and a subordinate of Demon Lord Milim Nava.
As a harpy, Frey has wings on her back and talons as feet. She has white hair and is usually seen wearing a red dress.
Frey is careful and cunning. Together with Milim, they easily outwitted Clayman by making him believe he had control over them, and even had him convinced that Carrion was dead, with the goal of unraveling the identities of the ones pulling his strings.
Frey became a self proclaimed Demon Lord around the same time as Clayman and Carrion and as such is regarded as one of the youngest Demon Lords of the Ten Great Demon Lords. Like Clayman and Carrion due to her being one of the youngest Demon Lord's, Frey became one of the most active Demon Lord's in increasing her personal power base in an attempt to bridge the gap between herself and the older generation of Demon Lord's and as such is one of the most well known Demon Lord's across the world for her exploits and power.
Frey herself established her own kingdom and is the queen of harpies and other winged creatures of the world. She was initially not involved in Clayman's plan of making a new puppet Demon Lord but later on choose to join in order to boost her own influence as well.
As a Harpy, Fray possess the ability to fly and is noted to be highly agile and extremely skilled in aerial combat. As a Self-Proclaimed Demon Lord, Frey's overall power should amount to that of a Demon Lord Seed. Making her extremely powerful and only surpassed by True Demon Lords.
- Magic Jamming (魔力妨害 maryoku bōgai, lit. "Magical Power Interference"): This skill grants Frey the ability to disturbs the flow of Magicules around herself. Making her strongly resistant to Magic and disturbs any external uses of Magicules while within her effective range of her skill.
- Milim Nava: Frey cannot work against Milim. Though they were both Demon Lords, there is a clear difference in power. Also being a Dragonoid Milim's flight cannot be canceled out using magic jamming. Truly her natural enemy. Hence, she became Milim's follower. After her expulsion, she officially became Milim's direct subordinate. Despite being Milim's subordinate, Frey acts more as a mentor to Milim, instructing her on how to rule over her newfound land. Milim, however, often escapes Frey's lessons to join her bestie, Rimuru, causing Frey to frequently scold her.
- Rimuru: Frey has a neutral view of Rimuru at best and appear to get along.
- Clayman: Frey considered Clayman to be a cunning and tricky opponent to handle. Although she bore no hate for him, she didn't pity him either when Rimuru overwhelmed him and took his life.
- Carrion: Her fellow former Demon Lord, workmate under the same master.
- Charybdis: Frey's natural enemy who possessed the same intrinsic skill as the harpies: Magic Interference. This skill negates the tactical advantage of the harpies' flight, making Charybdis their natural enemy.