Born into a family of musicians, Procella member Rui Minazuki and his older brother Rei were taught piano beginning at a young age.
Rui was quickly praised as a prodigy, but Rei was devastated by his brother`s talent and abandoned the path of music.
Because of that, the two were alienated from one another for a long time, but currently the bad blood between them has been resolved, and they`re back to getting along as brothers.
One day, Rui is asked to perform a piano recital as part of promoting the Full Moon Festival.
Together the members of Procella brainstorm ideas for the recital, and they go to visit Kai on the job in order to get his opinion as well.
By coincidence, this outing takes them to the university hospital where Rei works...