The "elite student in music room 2" turns out to be Haruki's delinquent classmate, Kazusa Touma.  With his characteristic pushiness, he tries to get her to join the light music club.  But his pushiness backfires, and only makes her more annoyed.  Setsuna gets irritated... no, involved, and approaches Kazusa secretly.
My guess is that she was 
attracting too much attention.
Ich schätze, sie hat zu 
viel Aufmerksamkeit erregt.
Supongo que atraía demasiado la atención.
Supongo que atraería demasiado la atención.
Je suppose qu’elle ne voulait pas 
attirer l’attention sur elle.
Meu palpite é que ela estava
chamando atenção demais.