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.
That's the kind of sneaky thing you'd do.
So eine hinterhältige Aktion 
würde zu dir passen.
Es la clase de trampa que usarías.
Es la clase de estratagema que tú usarías.
Ça te ressemble tellement…
É o tipo de truque sujo que você usaria.