It's possible that this doesn't end up like the hentai doujin. Kanzaki didn't see them screw (which lead to her having sex and being a quick squirt) because she was hanging out with the new protagonist after all.
Though, I hope he at least gets to screw the teacher.
If, there is an alternate world, then this timeline surely is the best one. And if there weren't any, then I sure am blessed to have been born in this century to witness upon this scene.