Campanella (カンパネルラ, kampanerura), also known as The Fool (道化師, doukeshi), is associated with Ouroboros as Legion No. 0. Although Campanella has the appearance of a young boy, he has not changed in over ten years. Although he is referred to as a male, neither his sex nor his age are certain. His left eye is always covered by his hair. He is the right hand of Ouroboros' Grandmaster, to which he reports the progress of the plans.