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.
Half of all people have their 
first kiss by high school.
La mitad de todas las personas tienen su primer beso en secundaria.
La mitad de la gente su primer beso suele ser en secundaria.
Metade das pessoas têm seu primeiro
 beijo no Ensino Médio.