From The Queen 2 Hearts:

Once upon a time when gods' world is so close to the Earth. There are four god families symbolize East - West - South - North called Seiryuu, Byakko, Suzaku and Genbu. Kira is original god of Kouryuu - the central god family which is the most powerful. Someday, while travelling with his brother, Kira met with an accident which made him lose power and felt to the Earth. Later, while looking for the way to return Heaven, Kira met Shana and Senju. Shana is a boy who has a half of his body immortal, whose sister is kidnapped and he is on the way hunting his enemy. Senju is a female disciple of Sara - a predictor who has a half blood of god. After Sara was kidnapped by Seiryuu King, all of three persons also find the way come to Heaven so that save her and wipe out their enemies.