Osamu Nishi

Osamu Nishi is a Japanese manga creator best known for *Welcome to Demon School! Iruma-kun*, titled *Mairimashita! Iruma-kun* in Japanese. The series began serialization in Akita Shoten’s *Weekly Shonen Champion* in March 2017. It follows Iruma Suzuki, a fourteen-year-old human whose irresponsible parents sell him to the demon Sullivan. Instead of harming Iruma, Sullivan adopts him and enrolls him at Babyls Demon School, where Iruma must conceal the fact that he is human.

Nishi’s central premise creates the series’ distinctive conflict: ordinary behavior from Iruma is repeatedly interpreted by demons as evidence of extraordinary courage or ambition. He initially tries to avoid attention, but his friendships with Asmodeus Alice and Clara Valac, along with his experiences in the school’s Misfit Class, gradually place him in increasingly important situations. The story uses Babyls’ ranking system, magical lessons, school festivals, musical performances, and the dangerous Harvest Festival to develop Iruma from a passive survivor into a student capable of making deliberate choices.

The manga’s recurring world-building includes demon ranks, magical bloodline abilities, flying bats, magical devices, and the history of the Netherworld. Iruma’s ring, which contains the demon Amduscias? No—the ring is called the Ring of Gluttony and houses a familiar-like entity known as Ali-san. Nishi also established a major secret around Iruma’s identity: humans are treated as legendary or dangerous beings in the Netherworld, so discovery could radically alter his position at school.

An anime adaptation produced by Bandai Namco Pictures premiered in Japan in October 2019. Its first season adapted the early Babyls material and introduced the principal cast, including Iruma, Sullivan, Kalego, Asmodeus, and Clara. A second season followed in 2021, and a third began in October 2022, covering the Harvest Festival arc and its preparation. The television adaptation brought Nishi’s manga to a wider international audience while retaining its school-comedy structure and fantasy setting.

Nishi’s work is notable for combining a vulnerable protagonist, a large ensemble of eccentric demons, and plot developments that repeatedly convert embarrassment into character growth. Rather than treating Iruma’s lack of demonic power as a permanent weakness, the manga makes his human adaptability, empathy, and willingness to protect others central sources of strength. The result is a long-running school fantasy whose specific rules and relationships grow directly from Nishi’s original human-in-the-Netherworld premise.