First impression: ^^
So? I saw the cover page, I knew it was going to be intense and hardcore on the ecchi, but I didn't think it would be pushed to the reasonable limits of ecchi. The author of this manga could have gone up one step further and it would have been a hentai.
In any case, you shouldn't read this manga in public and you should be at least 16 years old to read it (I'm just warning you, and again, I'm not up to date so let's say 16 - 18 years old in reality).
Regarding the story and development:
It's a comedy, you know. That's why the situations are absurd.
It's so absurd that it becomes funny when you least expect it, and so, when I read it, I go into a twisted guessing game mode, like, what can the high school girls do worse at that moment of the day for the teacher and how. I put myself in and think like the author of this particular manga.
Design level:
The characters are not very distinctive, I feel like they all have the same face and are drawn the same. Otherwise, the line, the details, and everything are great.
In summary, it's a well-drawn manga, hard and intensely ridiculous on the ecchi, the story is meh, and character development is lame. If you just want to see well-designed ass, this is where it happens.