The Church of Necessary Evil or Necessarius (必要悪の教会ネセサリウス Hitsuyōaku no Kyōkai (Nesesariusu), lit. "Church of Necessary Evil") is an international security organization and is the main magic side protagonist faction of the A Certain Magican Index series. It is the 0th Parish of the English Puritan Church and serves on behalf of both the Anglican Church and the British Royal Family with the intent of supressing the presence of magicians and magic all throughout the United Kingdom. Members of Necessarius make up the vast majority of Touma Kamijou's allies and are often seen fighting on his behalf and are the de facto magic side protectors of Academy City.