The song describes ARiA, an entity that seeks to be one with the stars. She saw a star during her childhood, and wishes to meet it once again. The song continues with ARiA trying to reach the heavens, using computer methods and technology. She sings her requests to the Eternal Sky wishing for miracles so she could see her precious star. She then flies into space, hoping to find her star, only to make her mysteriously disappear into its vastness.
The songs interpretation is a deep meaningful one, It may range from a person to always dream and reach high, to reach what they seek and to grow into the person they want. As one reaches their dreams and goals, they soon disappear into their own dream, where they might be happy or pleased to have reached what they have wanted to achieved for a long time. It is also notable that in the final line of the lyrics, the kanji for "star" (星) is used but is sung as moto ("source", e.g. "where someone is from")
The person depicted in the PV is not Miku. Her name is ARiA, a character made by the members who produced the work. The wearable supercomputer she uses is also called ARiA, in this case it's short for "Autonomous Reactive integral Attribute".