The Four Archangels (四大天使Yondaitenshi) are a group of high-ranked Angels in the White World.
Z/X Encyclopedia Entry
The organization resting at the apex of the White World, it consists of the first Angel "Uriel A.T.", and the three Angels who were "awakened" by Uriel (Raphael, Gabriel and Michael).
Each of the Four Archangels awoke three Angels themselves, the twelve newborn Angels were known as "The Twelve Apostles" and became the rulers of the White World. Below is which Angels of the Twelve Apostles were awakened by The Four Archangels.