Shun's younger brother Fuyuki and his girlfriend Mamiya-san kissed.  When Shun finds out, he asks his friends what he should do as Fuyuki's older brother.
Fuyuki ignores his brother and goes on a date with Mamiya.  The gang decides to follow the couple on their date and end up at a karaoke box.
Listen to what Mother Shun's saying.
Escucha lo que la madre Shun dice.
Escucha lo que la madre Shun dice.
Escute o que a mamãe Shun diz.