EXA_PICO (エクサピーコ, ekusapiiko?, lit. "EXA_PICO"), misromanized as Exa pieco in the localization of Ar tonelico II: Melody of Metafalica and as Exapico in the localization of Ar nosurge: Ode to an Unborn Star, is the point of origin for the universe shared between the Ar tonelico series and Surge Concerto series., as well as the name for the Seventh-Dimensional being that oversees and rules over it.
According to the current knowledge the Wave Science researchers have, EXA_PICO is an atomic nucleus with an incredible density, which many millions of years ago, contained all of the wave forms that comprise the universe. Then at a certain point in time, all of the waves it contained broke off from it in a massive explosion, which is the Big Bang that created the universe. This formed all of the Dynamic Waves, which are the undulating waves that comprise energy, and when all of these waves clashed with each other in the complete emptiness of the space of that time (the Sea of Num), they gave birth to the Static Waves, which went on to group themselves and form the first atomic nuclei, molecules, and thus gradually giving birth to all kinds of matter.
Even today, EXA_PICO and its waves (its Will) have influence over the entire universe, dictating the rhythm and beat under which the galaxies, planets and even the life forms of Ar Ciel and Ra Ciela dance. Said Song played by EXA_PICO is what the Teru of Ar Ciel call the Grand Wheel of Fate. However, not all the Wills that rule the galaxies and subordinate structures to them agree to everything that the Will of EXA_PICO says, which also changes their destinies.