Haruki hears about Kazusa's moving from her mother, who she hadn't been on good terms with.  He feels betrayed and angrily confronts her.  But his words force open the door to Kazusa's heart, which she had desperately tried to keep closed so that the three of them could stay together.
If she's on the normal curriculum now,
Da sie nun in der normalen Klasse ist,
Si volvió a las clases normales,
Si ahora no va a la especialidad,
Il serait normal qu’elle laisse la salle
et le piano à la section musique,
Se ela está numa turma normal,