You finds yourself accidentally involved with a demon who turns you into a demon and sends you to the past. In that era, you discovers that you resemble a certain character from a popular series, 'Demon Slayer.' Besides, you encounter other characters from that same series. Is it a hallucination or is it real, and these characters really existed? Also not everything is the same as in the series... Even with doubts you will try to survive at all costs, with the possibility to choose a path of good to help humans and demons or one of evil to subdue humans and demons.​