I don't think there would be more of the second couple because the extra is a flashback and the kid grows up to be Inoue-sensei of the track and field team. Inoue is the name the kid adopted after the divorce of his parents. He probably became a teacher because of his love for Nakatani-sensei but at the same time he knew that confessing wouldn't change anything because the only one Nakatani-sensei loves is his little brother (brother complex) all the others are just playthings. Nakatani-sensei like the boys he sleeps with but at the same level he likes a cute pet. They are cute but just pets little interesting things. Even Inoue that seemed to be a little more special by acting different and not falling immediately for Nakatani-sensei (what picked sensei's interest) wasn't special enough to make sensei change his attitude. In the time the main history happens Inoue-sensei probable feels a mix of admiration and repulse towards Nakatani-sensei.
I don't think there would be more of the second couple because the extra is a flashback and the kid grows up to be Inoue-sensei of the track and field team. Inoue is the name the kid adopted after the divorce of his parents. He probably became a teacher because of his love for Nakatani-sensei but at the same time he knew that confessing wouldn't change anything because the only one Nakatani-sensei loves is his little brother (brother complex) all the others are just playthings. Nakatani-sensei like the boys he sleeps with but at the same level he likes a cute pet. They are cute but just pets little interesting things. Even Inoue that seemed to be a little more special by acting different and not falling immediately for Nakatani-sensei (what picked sensei's interest) wasn't special enough to make sensei change his attitude. In the time the main history happens Inoue-sensei probable feels a mix of admiration and repulse towards Nakatani-sensei.