Kaim, also known as Caim or Kaimu, is a demon from the Devilman franchise whose loyalty and capacity for self-sacrifice distinguish him from many of his kind. Visually, Kaim is a massive, quadrupedal demon with an appearance often compared to a pachyderm or a bison. His entire body is covered in thick, armored plates with dark detailing, and he possesses a long tail along with a pair of large, black horns positioned near his shoulders. This imposing physical form underscores his nature as a powerful entity, though later depictions in some adaptations, such as Devilman Lady, show him with a more jagged appearance and the ability to fly by releasing blasts of fire from his legs.

Kaim's personality is the most defining aspect of his character. Unlike many demons who are portrayed as inherently evil or solely driven by malice, Kaim is not considered evil and only engages in combat when necessary. His actions are motivated by a deep and devoted love for his fellow demon, Sirene. He is quietly devoted to her, and his ultimate motivation is her well-being and her triumph. This devotion overrides any instinct for self-preservation, making him a tragic figure willing to pay the ultimate price for her victory.

In the story, Kaim plays a relatively minor but pivotal role during the conflict between Sirene and the protagonist, Devilman. After Sirene is fatally wounded in her battle, she flees and begs for aid. The Demon Lord Zennon responds by sending a horde of lesser demons to distract Devilman, and among them is Kaim. Finding a dying Sirene, he makes a desperate proposition. In the world of Devilman, demons can merge with one another, but only one consciousness will survive and control the combined body. Knowing that Sirene is too weak to endure the process, Kaim offers a solution. He confesses his long-hidden love for her and then kills himself, typically by ripping off his own head with his tail, to ensure that her consciousness will be the sole survivor of the fusion. This act allows Sirene to merge with his powerful body, creating a centaur-like creature that nearly defeats Devilman before Sirene's original wounds finally cause her death.

Kaim's key relationship is solely with Sirene, for whom he harbors an unrequited love. His entire existence within the narrative revolves around her, and his character development is encapsulated in his single, defining action. He transforms from a silent observer to a proactive savior, demonstrating a depth of emotion that complicates the typical portrayal of demons in the series. His willingness to sacrifice himself for love serves as a powerful counterpoint to the series' often bleak and violent themes, showing that even among demons, profound loyalty and affection can exist.

In terms of abilities, Kaim is a physically formidable demon, ranking among the strongest of his kind, though not on the level of a demon like Amon. His main assets are his immense physical strength, his speed when charging, and his powerful horns. These horns are not only used for skewering foes but are also capable of emitting powerful energy bolts or lightning. His tail is also depicted as a strong and useful appendage, capable of grabbing objects, including his own head. After merging with Sirene, their combined strength is enough to push Devilman to the brink of death, showcasing the significant power Kaim possessed even as a sacrifice. The name Kaim is derived from Caim, a great president of Hell from demonological grimoires like the Lesser Key of Solomon.