I bet my left foot, that at some point in the manga, the author with have the chad fuck the gyaru. If I was a betting man, he probably already did too.
@bvdaf I'm pretty sure that is not the author's intention to put himself as a villain. If anything it seems like the gyaru, Gotou, and the kouhai are the voice of the author preaching to us. Selfinserts are not as prominent in Japanese stories, at least not as much as they are in western comics and cartoons.