Long ago there was a war between the humans and the angels. After the angel Apollonius fell in love with the human Celiane, he tore the wings off of his back and helped humanity by creating the only machine capable of fending off the angels: Aquarion. He was eventually defeated by one of his comrades. Twelve thousand years later, the angels have returned to once more take the life-force of all humans. Aquarion's whereabouts are unknown, but humanity is fighting its hardest until the keys to victory can be found. In order to defeat the angels they need the aid of Aquarion and the re-incarnations of the lovers that saved humanity before, Celiane and Apollonius.
Mankind is close to being wiped out from the face of the earth from a being known as Festum. Tatsumiyajima Island is a calm place where children can live their lives at peace, but the inhabitants must now move into combat to keep the citizens safe from the Festum assimilating them. Kyo and Yumi are average students who have signed up for Plan L: an operation to fight for their island using the new Fafner TSX model. Together, the 8 pilots and 4 Fafners will fight to preserve both the peace of their island, and their faith that one day, they will make it home… alive.
Both of them are OVAs that take place BEFORE (in cronologic time) of the main serie, even if Aquarion OVA is also a retelling. The story focuses on relationships that are really tragic, both are moving to tears and with sci fi - mecha hints.
They will clear the story about the original serie if you want to. Again the world is awaiting to be saved.