At last, Haruki sleeps with Kazusa.  Her wish finally comes true, and she prepares to leave for Europe. Haruki takes Setsuna to the airport, hoping that they can all be together once again.  When the three are reunited, everyone remembers the best moment of their lives: the last song they sang at the school concert.  The title of the song was...
That's the only reason I volunteered 
myself as your girlfriend.
Das war der einzige Grund, aus dem ich 
mich als deine Freundin angeboten habe.
Es la única razón por la 
que ofrecí ser tu novia.
Es la única razón por la 
que me ofrecí a ser tu novia.
C’est la seule raison pour laquelle 
j’ai voulu sortir avec toi.
Só por isso que eu pedi para
 namorar com você.