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.
Who do you think you are?
Für wen hältst du dich?
¿Quién te crees que eres?
¿Quién te crees que eres?
Tu te prends pour qui ?
Quem você pensa que é?