Makai Ouji: Devils and Realist

William Twining is the orphaned son of the Twining family, one of Britain's oldest and most noble lines. When he learns his tuition has yet to be paid, he returns home to find the family in crisis - his uncle, inheritor of the entire estate, has gone bankrupt and disappeared. Searching the house for anything that might help him pay for school, William stumbles upon a hidden basement room and inadvertently summons a demon, Dantalion, who informs him he is the "Elector;" the one and only person who can appoint an interim leader of Hell.