Every October 31st, a powerful demon will manifest itself to bring chaos to the world. A seductress who excels at videogames, Mewtsukki can charm any person to do her bidding. On top of the highest room in the darkest castle, she looks down to find her next prey. However this skill can only happen on this specific day, turning into a normal VTuber on the next day. What? You say it's not October 31st? Impossible, hahahah! You're joking... Right?