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.
I don't know what to say to 
him as his older brother.
Como su hermano mayor no sé como decírselo.
Como su hermano mayor que soy, no sé como decírselo.
Não sei o que dizer a ele 
como irmão mais velho.