-Soleil- was first uploaded on June 25, 2012; without a PV. It was uploaded as one of "Miku's Creator" Project on Google+, and Toraboruta-P was one of the first producers interviewed and invited to the project. The project took three months with steps and tutorials uploaded for the song by Toraboruta-P (Matsumura Takumi also made a brief introduction to the flute for the song to Soleil).
Although the song was finished on June 25 and was uploaded to Toraboruta-P's YouTube; it was incomplete for the PV was scheduled to take another month as well. CHRIS, like Toraboruta-P, set deadlines such as "finishing illustration", or "begin video making". There were stages of concept arts as shared by CHRIS. Later, on September 11, the PV was finished and Toraboruta-P uploaded it to his Niconico account and YouTube.
Like many other Toraboruta-P's works, his song tells stories; much like Kokoro, or Soratobazu. The song tells a story of a girl (Rin) who wanted to save people in despair (from darkness). She finally collapses before being saved by the boy (Len) who uses part of her darkness to fly them up towards the sun before collapsing himself. The song's title: Soleil, comes from the French for 'Sun'.