The Ar Tonelico series takes place on the planet of Ar Ciel. Due to a prior catastrophy, humanity is forced to take refuge on one of 3 towers, called Ar Tonelico, located around the planet.
Ar Tonelico I takes place on Sol Ciel
Ar Tonelico II takes place on Meta Falas
Ar Tonelico III takes place on Sol Clusta
Sol Clusta is dominated by Reyvateils which are the ruling class. The ideal world to them consists only of Reyvateils and purified humans (ie. slaves)
Characters
Saki - Heroine (CV: Gotou Mai)
Reyvateil who was created in a laboratory for a plan that would have far reaching effects on the world (unclear if it's limited to Sol Clusta or the planet of Ar Ciel). She manages to escape shortly before the plan was to be set into motion and runs into the protagonist after being on the run for a number of years. When under sever duress, she exhibits a power called "miracle" on occasion.
Finnelle - Heroine (CV: Kitamura Eri)
βtype reyvateil (no human bloodline) born in the kingdom of Clustania. Ditzy girl who works in a restaurant on Tocociez Highway (i think?). Her existance appears to have a connection with the Clustania conspiracy but...
Aoto - Protagonist (CV: Sugiyama Noriaki)
Is an apprentice of a master who specializes in construction at high elevations. Doesn't think about consequences when he acts, but has a strong sense of obligation to complete what he's started. Has always had a slight dislike of Clustania, but after meeting Saki, he starts viewing Clustania as an enemy.
Hikarigojyou (Hikari Gojyou?) - Seen in screenshot
Tatsumi - Seen in screenshot
RAH System (Hymnos Synthesis) See link for some minor stuff
This title's Hymnos isn't limited to heroines just "singing" them. If you "combine" hymnos parts that are bourne from the heroine's psyche, the player himself/herself can create hymnos. Merging this RAH system and player's actions, the real-time BGM changes, which the Active Music Generation System accomplishes, brings a presence never experienced before (I'm assuming in regards to game BGM). Creating a good hymn and having the heroines sing it will bring effects such as increasing the vanguard's attack power.
Misc
Some other things I can't make out too clearly or don't deserve their own section.
-Deeper bonds with reyvateils allow them to "unleash" their attire which is probably what is being shown with the twin tailed girl (Finnelle)
-As before, the deeper you dive into the heroine's psyche, the more song magic you can unlock
-Multiple personalities (not sure if singular or plural) exist within each reyvateil. Different personalities prefer different song magics, which will have an effect on the RAH system.
-Aoto's town is at the border of the tower's climate control system, thus it's not completely protected from the elements, resulting in violent winds. The town has wind mills to make use of the winds, however.
-Clustania has the highest level of ameneties in the tower of Sol Clusta and is the central location for Reyvateils. Humans are brought into Clustania to help further develop Reyvateil's skills. Also, anti-Clustania individuals are brought in for cleansing.
-Jumping (i think?) returns to AT3
