In March, at the age of 17, Nina drops out of high school and moves to Tokyo on her own. She's completely lost in the big city. She was encouraged to come here after hearing a certain song she found online. The day she arrives, Nina meets the street musician who plays that song.

The three girls practice to level up as a band. Nina is obsessed with beating Diamond Dust, and researches ways to increase their popularity, but she fails to find anything good. That's when Tomo and Rupa approach Nina after having been to see the three girls perform the other day.