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.
Middle schoolers should study 
together, support each other,
Lo que deberían estar haciendo los de secundaria es estudiar,
Lo que deberíais estar haciendo los de secundaria es estudiar,
Alunos do Ensino Básico têm que 
estudar juntos, se ajudar