Rain

Originally one of the primal demons, Blue (ブルー). In ancient times, she challenged Guy along with Misery, was defeated, summoned by Guy, given a name, evolved into a Demon Duke, and became a loyal maid to Guy. She appears as a beautiful woman with blue hair, wearing a dark crimson maid outfit. Her name is derived from "blood rain." In Volume 17, Chapter 4, she serves as the narrator.

In Volume 6, during the Demon Lords' banquet, she acts as the moderator of the meeting, and in Volume 11, she fights Diablo but is overwhelmed. Upon learning that Rimuru has added Testarossa, Ultima, and Carrera to his subordinates, she places Rimuru at the top of her list of beings to be wary of. Originally fond of slimes, she had a favorable impression of the capable Rimuru, but her admiration for him increased during her visit to the Jura Tempest Federation in Volume 14, thanks to Rimuru's polite and considerate treatment, leading her to be surprised and vow cooperation when Rimuru awakened her to evolve into a Demon Lord.

In front of Guy, she pretends, but her true nature is self-centered with a youngest child temperament. Volume 17 discusses her lazy and careless personality, her enjoyment of Guy's troubles, her desire to always be on the winning side, her hobby of drawing abstract paintings that annoy the model Misery, and her hobby of enjoying a vacation mood in the extremely cold White Ice Palace by keeping it in perpetual summer mode inside a "barrier." Additionally, her inner thoughts reveal her discomfort with Diablo, who drew with Guy, her harsh internal criticism of the troublesome ancestral vampire and the lazy Dino, while showing respect for Luminous and Ramiris.

Misola

A demon under Rain's command. She was the top subordinate under Rain and a high-ranking demon general at the time of Guy and Leon's meeting in Volume 6, but by Volume 18, with the awakening of her master Rain, she has become a duke-level Demon Duke. Originally the same duke level as Testarossa's subordinate Moss, she was inferior in strength, and unlike Moss, who became a grand duke due to the master's awakening, her rank remained as a duke. Although she is a hard worker tormented by her master Rain, she adores her master, and Rimuru, seeing this, compared her to Trainee, who spoils Ramiris.

During the Great Demon War, she fought Vega along with Leon's subordinate Metel and three other Demon Dukes in Eldorado. Despite being overwhelmingly powerful, they managed to hold the line until Ranga, who came to their aid, allowed them to survive. Impressed by Ranga's strength and his master Rimuru, who easily forced Vega to retreat alone, she developed a deep respect for Rimuru.

Skoll, Ulrich, Alban, Georg

Demons under Misery and Rain. They were high-ranking demon generals at the time of Guy and Leon's meeting in Volume 6, but by Volume 18, they had become Demon Dukes due to the awakening of Misery and others.

During the Great Demon War, they fought Vega along with Misola.

Ivy

A demon under Rain's command. She has not appeared in the main story but appears in the spin-off "Clayman REVENGE." She holds the position of a marquis in the Kingdom of Ingracia. Her rank as a demon is unknown, but it is confirmed that she is a high-ranking demon general.