Hi it looked like there wasn't any forum topic for this manga. So there it is. I just read all 6 chapters in one go and wanted an actual place to discuss it.
I think the two protagonist may come to love each other even with the rule they set up, also the two teachers are clearly into one another, and then come the two friend that just want one of the two MCs for themselves. I wouldn't be surprised if the two girls became girlfriends out of substitute... (the yuri girl and the princess girl) Would be funny if the two teachers actually are into their student but will go out with each other because of morality.
Substitute everywhere!