Nobody talks about this one. A priest and a nun walk into an impossible miracle, and the show treats the investigation like a locked-room mystery instead of a sermon. By the end, faith itself becomes the unreliable narrator, and you're left holding a case that refuses to close.

Roberto Nicholas is sorting through old documents when he finds an unusual record. It describes a pact with a witch who escaped the cruel witch trials by brewing a soup said to give generations of popes long lives. Roberto wants to know why the Vatican kept the record so secret and whether the longevity elixir is real, so he and his partner, Josef Kou Hiraga, set out to make the soup again. The story is a single OVA episode of supernatural mystery and drama, released with the 17th volume of the novel.