Hibiki, explain everything to sensei and Chigusa already! Stop running after that snake! And, let's say the truth: Nagisa was a trouble since the beginning, it was just a matter of time for him to be such a desappointment. His "love" is so deep that he doesn't have any patience and easily belives in lies.
I also think Kousuke often say wise things, and if it wasn't him, these girls would be thrown back and forth all the time.
But... why no one in this manga communicate? For the sake of the drama 😩😡