To commemorate the broadcast of the fourth season of the anime *Demon Slayer: Iruma-kun*, a collaboration event will be held at the Shinjuku Prince Hotel and the Kawagoe Prince Hotel from September 1 to October 31, 2026. With different themes for each hotel—”Demon World Hotel” in Shinjuku and “Music Festival” in Kawagoe—the event will feature themed room packages, afternoon tea, and collaboration menus.