君を捜す空 (Kimi wo Sagasu Sora)

Background
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.

This song is featured in EndlessroLL and Hitoshizukushi, Hitoshizuku-P's first album. It has entered the Hall of Fame.