"Kuroshitsuji," also known as "Black Butler," is a Japanese manga series created by Yana Toboso. It follows the story of Ciel Phantomhive, a young nobleman who makes a pact with a demon named Sebastian Michaelis. Together, they seek revenge against those who wronged Ciel, with Sebastian serving as both his butler and protector. The series is set in Victorian-era England and blends elements of fantasy, mystery, and dark humor. It has been adapted into an anime series, several stage plays, and live-action films, gaining a significant fanbase worldwide. The themes of loyalty, betrayal, and the supernatural are central to the narrative.