This is...based on? inspired by?....anyway, the lyrics are from this song, by EasyPop (a Vocaloid producer, probably most famous for Happy Synthesizer featuring Megurine Luka and Megpod, aka Gumi) featuring Hatsune Miku. It's basically about not crying over yesterday but working toward a better tomorrow instead.

My best friends and I were known as the Powerpuff Girls in high school and right now out Bubbles is having a bit of a hard time so...this is for her.