Watch Saint Beast: Ikusen no Hiru to Yoru-hen Online

Long ago there was a war in Heaven which resulted in Judas and Luca – two of the six specially-chosen, talented and strong Saint Beasts – being cast out and imprisoned in Hell for leading the rebellion. But before that Heaven had been a peaceful place where the angels happily lived their lives. In this time, Judas, Luca, Goh, Shin, Rey and Gai are adolescent angels in Heaven who, on the day of Benediction, are made into adults by the supreme god Zeus. With each of the six having their own special abilities and new adult bodies to get used to, opportunities to meet each other arise and new friendships are formed.

A long time ago, Zeus, the great god, created a three-tier hierarchy of angels, top, middle and lower, although they were supposed to be equal. And Zeus also appointed 6 angels as Saint Beasts who govern the animals of Earth. They were: Gou, the seiryuu; Shin, the genbu; Rei, the suzaku; Gai, the byakko; Judas, the kirin; and Luka, the houou. However, Kira, the shooting star, and Maya, the fuuga, did not attend the selection tests and left for the Earth.The six angels fulfilled their tasks faithfully. However, because of Zeus' increasingly tyrannical acts, they begin to mistrust him.Source: AnimeNfo

In the ancient past, the Highest level of angels, the Six Saintly Beasts reigned supreme as the beast kings. Two of the Saint Beasts disobeyed Gods order and was sealed away in a Hellish place. Now after thousands of days and nights, the barrier has weakend and they escape. So the remaining four must go to Earth and stop them from causing trouble.