The Covenant of Elemia (エレミア誓約書, eremia seiyakusho?, lit. "Covenant of Elemia"), also called the Contract of Elemia, is a document written by the Humans and Teru that cooperated to seal Mir, which registers all the limits that were imposed on the use of the resources of the Tower of Ar tonelico. It was decided that all the usage of this extremely powerful facility was to be banned, so disasters such as the one that caused the end of the First Era: the Grathnode Inferia, and the one that caused the end of the Second Era: Mir's Rebellion, would never be repeated again.

As the representatives of the Humans, the job of the Apostles of Elemia was the administration and supervision of the Symphonic Reactor and the viruses that spawned from it. On the other part, the job of the Teru people was the supervision of the Crescent Chronicle and the protection of the Star Singer. Also, they had the job of preventing the humans that lived in the Wings of Horus from getting close to the essential facilities of the Tower without reason, and they did not have other choice than attacking the people that were stubborn enough to keep trying to climb the Tower after the Terus' warnings. Even if in the current times the humans and Teru have fought fiercely because of this, it was thought that it was a necessary evil for the sake of the world.