The Orsola Aquinas Rescue Arc is a major story arc in the Toaru Majutsu no Index storyline. It focuses on the rescue of the title character of the arc, Orsola Aquinas, a member of the Roman Catholic Church who has found a way to decipher the mysterious Book of the Law, a grimoire that is said to hold great power. The arc marks the first time Touma battles against the Roman Catholic Church, as well the first time two different Christian sects: Anglican Church (specifically Necessarius) and the Roman Catholic Church (specifically Agnese Forces) come into conflict with each other.