Legend has it that the Virgin Mary, the messenger and hope of the Roman Catholic Church, will reincarnate as a girl bearing "cross stigmata." Nagisa Akira has a cross-shaped mark on her chest, but to the best of her knowledge, she possesses no holy powers. Instead of being treated as a reborn saint, she simply wishes to be an ordinary schoolgirl. Akira was orphaned eight years ago and placed under the protection of the Japanese church, "Bethlehem." When the Vatican learns of her whereabouts, they dispatch an elite unit from their private army, the Crimson Cross, to serve as her bodyguards. One of them is Chrome Takagi, codenamed "Crimson," a prodigy with exceptional ability to handle demonic powers. At the same time the Vatican takes notice of Akira, she also draws the interest of the Tiamat Financial Group. Tiamat is supposedly controlled by demons, specifically nine immensely powerful "Numbers." Tiamat immediately pursues Akira, but their leader, Cyus, appears strangely more fixated on Chrome than on her.