Eh given he has switched classes he will more likely have at least 78 girls
Sou did not switch classes, the guards did.
But given how it usually works in schools where friends may go to different classes and girls meeting each other off screen, the gossip will take care of that soon enough. Sou will be made known across the whole academy. Best example would be Ruri as she had no clue about Sou but still knew there was a new guy in class E. That's why she tried to sneak a peek. She won't stay the only one who's curious. If a serious guard team like Aya's pulls a stunt like "class exchange" right after this new man joined the academy, that's gonna raise questions. Remember, this was probably never used before.
How will it develop? Who knows. One major incident will be the planned welcome party. If that event goes well, the class E ladies might start bragging about their husband afterwards - or they become very protective of him, to prevent more competition. Not to mention the commotion it would cause among the guard teams if another unit applies for class exchange as well. Team A will be sad they can't again and Team E around Miku will be seriously pissed.
Looking into the future - Ruri might not be allowed an instant class exchange right away, because it would affect Miku and her team if they have to leave their class again. Unless Akira is crazy enough to allow another exchange right the next day, it would be possible that the welcome party took place before Ruri comes to class E. In that case, Sou will definitely have deepened his bonds with the girls in class and Ruri is bound to face a serious problem if she tries anything funny. From a guard's perspective It's one thing to deal with one or two girls acting out of line. But here the whole class E would gang up on the guards - they'd be seriously outnumbered. The funniest would be a reversal where Sou has to protect the guards from the girls in his class.
we're not the wild ones, the mangaka is.
