We reflect Aoi's memory while she plays Bass and just wants to zone out from the noise of the world. She modified the song her teacher wrote her long ago, so she can honor his teachings.
Symbolism: Aoi as a child can only play "circles". Her teacher could play "squares". After her teacher passed away, she wanted to honor his legacy and learn her Teachers style of playing. She combined the styles and played her teachers old song "Aoi's Bassline".