In the Apocalypse texts, the seven angels will launch seven chastisements on human beings when the seven seals will be broken in order to open the book of God’s Wrath.
In the X/1999, Kanoe brought the seven angels together in order to start the “ Jour de la Promesse”. They are seven persons with one aim : to save the Earth and to destroy the humanity. That is why each angel has a natural ability which permits him/her to destroy kekkai in Tokyo. Also when an angel is killed, he/she will be replaced by a seal.