An oni (demon/ogre) is a fascinating supernatural creature. Depicted in Japanese literature, religion, art, and folklore, the oni’s longevity can be ascribed to their symbiotic evolution alongside Japanese society. The recent Japanese societal phenomenon created by Kimetsu no yaiba, a manga which was then made into anime and a film, reveals how oni still occupy an important position in Japanese culture. Kimetsu no yaiba depicts a war between humans and evil oni. The oni characters in Kimetsu no yaiba across all its iterations possess the fundamental attributes of traditional oni such as anthropophagy, but distinct attributes are added. These draw on cultural elements from the West, including superheroes and, most notably, vampires. This research note will focus on the characteristics of oni and their portrayal in Kimetsu no yaiba to demonstrate the ongoing evolution of oni and emphasize their continued relevance today.