This subject is a mistranslated title. This song is known as "I Look for You in the Sky" in the Western fandom, but "The Sky Where I Look for You" is more suitable. This tradition comes from Motokokusanagi's mistranslated title. More subjects categorized here.
The first song in the Synchronicity series. It tells of how Len was separated from his twin sister Rin at birth. When he grows older, his mother reveals him the truth and he decides to save her from her fate of singing for a dragon until she becomes devoured.