"Parallel Lines" is an original Luka song. It was written by Empath-P as an early demonstration song for the Megurine Luka V4X English Voicebank and MEIKO English in the harmony. However, it wasn't chosen by Crypton Future Media to be an official demo on Luka's page. The song was commissioned for Empath-P to write, and she reports that the full version will be sung by both AVANNA and YOHIOloid.