Haruki is entranced by Setsuna's singing on the rooftop, and plots to get her to join the Light Music Club no matter what.  But she hates standing out, so convincing her is incredibly difficult.  Meanwhile, the club has an even bigger problem.  The elite student from Music Room 2 he was trying to persuade to join his club as the keyboard player isn't a member of the Music Class, it's a mysterious person whose class and identity are a total unknown.
Do you think they actually know 
who's playing the piano?
Glaubst du, sie wissen, 
wer das Klavier spielt?
¿Será que saben quién está ahí?
¿Crees que saben quién la utiliza?
Je parie qu’ils savent 
qui utilise la salle.
Acha que eles sabem quem é?