"Welcome to Demon School, Iruma-kun" centers around Iruma Suzuki, a 14-year-old human boy who is sold to a demon by his neglectful parents. The demon, Sullivan, is the chairman of Babyls Demon School and adopts Iruma as his grandson. Despite being human, Iruma is enrolled in the school, where he must navigate a world of demons while concealing his true identity. Sullivan uses his influence to ensure Iruma’s safety, but the boy must still face the challenges of demon society on his own.

At Babyls, Iruma is placed in the misfit class, where he meets a variety of eccentric classmates, each with unique demon traits and personalities. Among them are Alice Asmodeus, a fiercely loyal and powerful demon who becomes Iruma’s closest friend, and Clara Valac, a mischievous and energetic demon with a knack for summoning random objects. Despite his initial fear and reluctance, Iruma gradually earns the respect and admiration of his peers through his kindness, resourcefulness, and willingness to help others.

The series explores Iruma’s growth as he adapts to the demon world, often finding himself in extraordinary situations. His unique human traits, such as his ability to evade danger and his capacity for empathy, set him apart from his demon classmates and frequently lead to unexpected outcomes. Iruma’s journey is marked by his participation in various school events, such as the Battler Party, a competitive festival, and the Harvest Festival, where students must survive in a dangerous forest. These events test his courage, intelligence, and ability to work with others.

A recurring theme is Iruma’s relationship with his classmates and his gradual acceptance into demon society. His bond with Alice and Clara deepens as they support him through challenges, while other characters, such as the ambitious and cunning Sabnock Sabro and the enigmatic Professor Kalego, add complexity to the narrative. Iruma’s interactions with these characters highlight the contrast between human and demon values, often leading to humorous or heartwarming moments.

The series also delves into the hierarchy and traditions of the demon world, with Iruma inadvertently rising in status due to his actions. His innate ability to inspire loyalty and his knack for solving problems earn him the title of “Demon King Candidate,” a position he neither seeks nor fully understands. This development introduces political intrigue and rivalries, as other demons take notice of Iruma’s potential.

Throughout the story, Iruma’s humanity remains central to his character, serving as both a vulnerability and a strength. His compassion and determination challenge the norms of demon society, often leading to positive change among his peers. The narrative balances humor, action, and heartfelt moments, creating a dynamic and engaging exploration of Iruma’s journey in a world where he does not belong but gradually finds his place.