Caim Kamui is a second-year student at Babylus Demon School and a member of the so-called Abnormal Class alongside Suzuki Iruma. He is a demon of the avian type, possessing an appearance that is distinctly bird-like. He has a beak, wing-like hands, and a generally fluffy quality to his head and body. His ears are comparatively cat-like, and two small horns sit atop his head. He wears the standard male uniform of the school, which includes a blue cape with white highlights and a demonic eye-shaped bow tie at the center.

Kamui's personality is defined by a sharp and often contradictory duality. On the surface, he is a self-proclaimed gentleman who speaks with elaborate politeness and strives to maintain elegant manners. In fact, his gentlemanly conduct is polished enough to be acknowledged by someone as particular as Alice Asmodeus. Beneath this refined exterior, however, lies an unrepentant and enthusiastic pervert. His blatant fascination with the female form, which he makes little effort to hide, has led to behavior such as trying to peek up classmates' skirts or sneaking into girls-only classes. This conduct is the primary reason he was transferred into the Abnormal Class in the first place. Despite his forward and often unsuccessful approaches toward female students, his original ambition is simple: to be popular, especially with girls. This desire has been a driving force in his life since childhood, stemming from a belief that acting as a proper gentleman is the surest path to gaining popularity and affection.

His background and motivations are deeply tied to his family history. The Caim family was once a clan of "barbarians" that used their unique power to lead an army of various beasts in a rebellion against the demon king of ancient times. After a fierce battle that nearly led to the clan's annihilation, the surviving Caim swore eternal loyalty to the demon throne and reformed themselves into models of chivalrous gentlemen and ladies. Kamui, having absorbed this family legacy from childhood, believes that adhering to a code of gentlemanly conduct is both an honorable tradition and the key to his personal ambition for popularity.

Caim Kamui plays a significant role within his class as a specialist in communication and coordination. His inherited family magic is called Translation, also known as Close Friends. This ability allows him to automatically understand and speak the languages of any living creature, from wild beasts to other demons' summoned familiars. The true essence of this power, however, is not just translation but command and leadership. During the Harvest Festival, he partnered with Kerori Crocell, where his role was to rally, motivate, and direct the horde of beasts that Kerori subdued and summoned. His skills allowed them to form a formidable "Beast Empire" and advance in the competition. Beyond his magical ability, Kamui has also demonstrated considerable physical durability, notably surviving a sustained magical assault from a teacher, Momonoki, during the Heart Breaker exam where he bravely defended a group of first-year students.

His relationships with other students are varied. He holds a respectful admiration for Iruma Suzuki, though he is often envious of Iruma's effortless popularity with female classmates. He has a rivalry-adjacent dynamic with Asmodeus Alice, who begrudgingly acknowledges Kamui's manners but has no patience for his perverted antics and is often depicted reprimanding him. His relationship with Crocell Kerori began with her being put off by his behavior but evolved into a strong and effective working partnership. After the training they underwent together, they became a highly coordinated team that combined her summoning abilities with his commanding voice.

Throughout the story, Caim Kamui demonstrates notable development. His initial reputation as merely a perverted student began to change after special training in preparation for the Harvest Festival. Under the tutelage of a teacher named Mister Hat, he honed his innate talents not as a summoner, but as a charismatic leader capable of communicating with and commanding magical beasts. His most profound development occurs during the Heart Breaker exam, where his flippant desire for popularity is tested. When tasked with protecting junior students, he displays genuine courage and self-sacrifice. By standing alone against a powerful teacher to buy time for his charges, he earns a moment of sincere admiration and gratitude from his teammates, fulfilling his wish for popularity in a way that transcends his shallow earlier pursuits. In terms of demonic rank, he started at Aleph, earned a promotion to Beth after the term-end finals, rose to Gimel due to his performance in the Harvest Festival, and finally reached the rank of Daleth alongside the rest of his class following the Music Festival.