The player is introduced to Ionasal (shortened to "Ion" in the game), a girl with amnesia; the player's objective is to help Ion regather her memories by entering her mind, which is shown as a broken world which the player can repair (in order to recover Ion's memories). Although not a continuation of the Ar tonelico series, it takes place in the same universe with many of the same elements and expands on the series mythos. Source: Wikipedia, "Ciel nosurge," available under the CC-BY-SA License.