The Hishouten (エレミア三謳神, eremia san'oushin?, lit. "Three Singing Goddesses of Elemia") is the trio of Goddesses worshipped by the Church of El Elemia. Said Goddesses are Eoria, Frelia and Tyria, and they were said to be able to create land, shoot fire and even heal people just by singing. Because of this, they were considered by the believers of the Church to be the creators of a great utopia in the distant past.
However, they have other legends far older than the ones described in the books found by the executives of the Church. In fact, the earliest legend in which they appear predates even the ones in which the demi-Goddesses Harvestasha and Rhaplanca make an appearance.
Said story is called "Festival of the Stars ~ Stelliarhythm ~", in which Eoria, Frelia and Tyria were depicted as some of the first human beings. They were three sisters who were bestowed the voice of the Gods in order to give hope to the people. It was also mentioned that there are other characters who helped them in their mission to make a better place of the world in which they lived. Each one of the three sisters had the power to control one of the elements: Eoria could control the wind, Frelia could control the earth, and Tyria could control the water. The three sisters were pretty known throughout the world, although they were given other names in Sol Cluster: Eoria was called Hishouten (飛翔天, hishouten?, lit. "Soaring Heaven"), Frelia's name was Hekijuten (碧珠天, hekijuten?, lit. "Jade Heaven"), and Tyria's was Kaibyouten (海淼天, kaibyouten?, lit. "Oceanic Heaven"). So far, no other details on this story have been revealed.
The Three Origin Reyvateils have their names based on these three mythological sisters not only because of being the very first and most powerful members of the Reyvateil race, but also, for being a source of hope for the humans like their namesakes were, since they would be the ones to control the three Towers of Ar tonelico, and harness the powers of the Songs in a way no one could even have dreamt of.