A man who loved the anime "Demon Slayer" dies after being depressed by the ending and is reborn into the world of Demon Slayer with an Otherworld Simulator. Despite his ordinary start as an unregistered citizen, he aims to defeat Muzan Kibutsuji. This story blends elements of Demon Slayer with other worlds, featuring a single main heroine (with potential for a harem), and promises a happy ending with Muzan's demise. Expect encounters with characters like Shinobu Kocho, Nezuko Kamado, Sasuke Uchiha, and Ichigo Kurosaki.