RahXephon

The backdrop of RahXephon is a fight against pan-dimensional invaders known as the Mulians, or Mu (ムー Mū). In appearance, the Mu are indistinguishable from humans. However, they carry a genetic marker called the "Mu phase" which makes their blood turn blue at a point in their maturity; this process also appears to cause memory loss.
The story reveals that two floating cities appeared above Tokyo and Sendai around the end of 2012. The ensuing conflict escalated into nuclear warfare, and the Mu enveloped Tokyo and outlying suburbs within a spherical barrier resembling Jupiter, referred to as "Tokyo Jupiter" ("Tōkyō Jupita") by all those outside. The barrier has a dilatory effect on time, with time inside Tokyo Jupiter passing about one-fifth as fast as the outside time.
Although RahXephon is part of the mecha genre of anime, its "mechas" are not generally mechanical. The mechas used by the Mu are called Dolems and are made of clay, like golems. Each is bound to a Mulian, and some are also bound to a human host called a "sub-Mulian".
The overarching theme of RahXephon is one of music changing the world. The Dolems are animated by a quasi-mystical force that is connected to music; most of the controlling Mulians appear to be singing. A Dolem attacks while singing, and sometimes the attack is the song itself. The RahXephon can also attack by having its pilot — the "instrumentalist" — sing a note. This unleashes powerful forces (such as light-energy blasts or heat waves) that cause destruction on an apocalyptic scale. Each of the Mulian Dolems has an Italian name which references musical notation, such as Allegretto, Falsetto, or Vivace. The ultimate goal of the RahXephon is to "tune the world." Izubuchi says the name RahXephon lacked a real meaning, but that he now explains it as composed of Rah, which according to Churchward is the origin of Ra, X for the X factor (the unknown), and -ephon as a suffix for instrument (-phone).

Free Downloads OST RahXephon
OP2 – Maaya Sakamoto – Hemisphere
ED1 – Ichiko Hashimoto – Yume no Tamago