The core part of the series is formed by three console role playing games, which are listed below in chronological order: The Ar tonelico series is set in a planet called Ar Ciel, which lost its land in a great man-made catastrophe a long time ago, and it is a work of science fantasy that depicts the interaction between the protagonist and the heroines, the latter generally being members of a race called Revatail (romanized as Reyvateil in the English-localized versions of the games and related material), which can use a special ability known as Song Magic.

[4] The first chapter in the series, released as a game for the Sony PlayStation 2, gathered quite an appreciation due to its depictions of several topics, beginning with the usage of the Hymmnos Language for its songs, followed by the union of an elaborate world setting with a charming cast of characters.

[5] The following games introduced new ideas to the formula while continuing with the established basis for the series, as well as also receiving expansions into multimedia territory with the release of material such as manga and Drama CDs, which having songs and music as their core, further expanded the already complex world setting.

However, the project was restarted later on as a collaboration with Banpresto, in which the aforementioned bels were simplified with the introduction of the synthesis recipes, and the main concepts to the series: "Grathmeld", "Reyvateil", "Cosmosphere" and "Hymmnos", were introduced.

The universe that serves as the setting for the Ar tonelico series differs from our own in that it was formed by the Song interwoven out of waves by the original atomic nucleus called EXA_PICO.

It also receives the name "Sol Ciel" in the Ancient Metafalss Note dialect of the Hymmnos Language, which translates to "shining world".

As the result of the great disaster known as the "Grathnode Inferia", the sky was covered with a layer of plasma called the "Blast Line", while the surface of the planet was pulverized and covered by a thick layer of clouds called the "Sea of Death", so the survivors to this catastrophe barely managed to escape death by clinging to the Towers and their surrounding areas, which became the only places where life could still thrive in Ar Ciel.

This region was a treasure trove of Songstones, as well as the point where it was the easiest to contact the Wills of the Planet, which led to it being called the "place where the truth of the world is gathered".

The Third Tower "Harvestasha", located in the region of Sol Cluster, was built to shoot the XP Shell into the Planetary in order to carry out the AAA Planet Regeneration Project, but due to several incidents that led it to lack the power necessary to finish its construction, it wasn't completed until near the end of the story of Ar tonelico Qoga.

The Song Server proper that houses the Soulspaces of the Sol Cluster Reyvateils is instead stored in the "Tower of Origin" located at Archia.

Originally called "Revatail" in the Japanese version, which comes from the Hymmnos word with the same pronunciation and meaning, they are a rare race that has appeared in all material related to the series so far and has the ability of converting sounds into power.

Every Reyvateil is connected to the Song Server they use as the source of their powers through an umbilical cord of sorts located in the deepest layer of their psyches.

All of them were born in El Elemia (the main country of Sol Ciel) during the First Era, and their abilities as Reyvateils surpass that of most of the other types by far.

Their names are taken from the three Demigoddesses known as the "Trio of Elemia" that appear in the Ar Ciel creation myth "Stelliarhythm", of which Eoria had the power of controlling the "wind", Frelia the "land" and Tyria the "water".

[10] Therefore, they alongside the Demigoddesses from which their names are taken are the main target of worshiping for the people of Sol Ciel, called the "Trio of Elemia".

However, the Rinkernator of the Third Tower of Ar tonelico is equipped with machines that allow to donate a large amount of Telomeres from a Reyvateil to other, making it possible to restore them to a depleted Triangular Nuclear Loop.

Strictly speaking, since they are just humans that were erroneously recognized as Reyvateils by the Song Servers due to their strong Reyvateil factors,[17] they typically are inferior to the Pureblooded β-Types due to the enormous difference in ability between each girl, which is why they are given a test called the Hexagonal Plate Test and from its results, they are assigned a rank that goes from A to D in Sol Ciel.

[21] However, there is an exception to this, as in the Sol Cluster region, the Neo Atlas Faction of Archia scattered several anomalous Reyvateil factors in preparation for the execution of their "Human Evolution Project", which fundamentally allows anyone to connect their minds to a Song Server regardless of gender or Reyvateil awakening, yet if these humans suffer a strong surge of emotion, they will fall into a condition that will cause them to go berserk and their minds completely destroyed.

On the world of Metafalss, Diquility was discovered and invented by the first Maiden of Mio, Infel, so the Grand Bell Hall began distributing it to all the Reyvateils in the region free of any charge.

Said distribution doesn't only cover the capital city of Pastalia, but also all of the areas of the neighboring Rim, which makes it an environment in which Third Generations can live without much problem.

However, the Install Ports themselves aren't visible in the in-game portraits or event stills due to design concerns, so as a general rule, they are never drawn for these kinds of art.

All of the Reyvateils can materialize their fantasies into the real world in order to use them as attacks or protection, normally using Hymmnos to do so, which receives the name Song Magic.

However, there is an exception to this, as in one of the sidestory Drama CDs, the character that appeared in the first game, Spica Neal, managed to craft a Song Magic that rivaled in power that of the Reyvateils through an item called the "Carillon Organito" that was made by a little girl that resembled Krusche Elendia.

[28] An identifier used for distinguishing individual Reyvateils among all that are connected to the Towers, and it is used during the authentication process that takes place during the Downloads for Hymmnos.

[33] The act of interfering with the Cosmosphere of a Reyvateil, which is made possible through the usage of institutions called "Dive Shops", which can be found in all the regions of Ar Ciel.

As the Divers who have reached the ninth level have been said to be rare enough that only a few of them live in each era, they apparently are considered as candidates to heroes just from having managed to complete a Cosmosphere to the end.

While the Munoph (Ayatane) Teru School was supposed to use their ability to predict the future in order to avoid the happening of disasters, they instead used it to trigger the catastrophe that served as the cause for the complete destruction of the civilization that thrived during the First Era: the Grathnode Inferia.

There are also half-breeds of Terus with humans and Reyvateils: they are descendants of the team of engineers known as the "People of Mio", and they used to live in the area known as Kanakana Pier.

On the world of Sol Cluster, the Teru school called "Munoph (Ayatane)" once prophesied that "the Reyvateils would take hold of the trigger for the restoration of the world", which is why they manipulated the Reyvateil country of Clustania from the shadows, but after the head of the Homuragi Necrofamily: "Homuragi Gentoku Rakujou", caused the "Ayatane War", the Archia Think Tank carried out a systematic extermination of all the living Necrofamilies, leaving them as forgotten existences.

Below is a simple explanation about the contents found in the official site "Ar Portal", which contains all of the following alongside developer's diaries and additional information about the game world.