Ar tonelico 2: Melody of Metafalica
centers on Croix, a young knight who is charged with finding a solution to Infel Phira Dependency, a disease that affects only Reyvateils. If you played the first game, you'll remember that Reyvateils are a race of song maidens who can cast powerful magic through their songs. These songstresses were a big part of the original and find their roles expanded even more in the sequel.
The first, and perhaps biggest, change is that you now have two Reyvateils in your party instead of one. Battles are divided into two phases, attack and defend. During the attack phase, you have to press buttons in time with on-screen prompts before time runs out. Once the meter is depleted, a similar button-matching system pops up, only now you have to keep the Reyvateils protected. Timing plays a major role during this phase; screwing up the timing of a button press will tick off your Reyvateils (who will happily show their displeasure), which, in turn will affect how powerful your attacks are. The happier a Reyvateil is, the more powerful she is.
Aside from the more traditional JRPG structure, Melody of Metafalica also features a fairly in-depth dating sim. Reyvateils are sort of like pets in that the more they trust you, the more you'll get out of them. In addition to earning their trust during battles (i.e. not getting them killed), you can also speak with them at save points. As you build trust, you'll earn the chance to "dive" into your Reyvateils' subconscious, known as the Cosmosphere. While in the Cosmosphere, you will face off with the Reyvateil's inner demons and help her resolve her issues. Successfully doing so strengthens her link and unlocks new spells. At times, you'll even use the Sphere to bond your Reyvateils. Though this usually relates to story elements, it will also unlock powerful dual spells.
Melody of Metafalica continues the first game's incredibly suggestive mood. There are a few lip-locks, some highly provocative language and even a mechanic that involves bathing. It's kept PG-13 and well within line of the game's "T" rating, but even then, the game attempts to get away with as much as it can.