Large cast my ass, complain all you want but they all are taking part in the story, introducing them early saves time for more important things so I suggest you stop complaining about large cast of characters. I've seen shows with much more characters tbh.
Were those shows any good, either? Seriously, not having the largest cast in any anime ever doesn't suddenly make Horizon's small.
It's a literal class room full of characters. Most of them aren't very important. They're never going to be very important. But they'll eat up screen time and detract from the plot. Which isn't very important to begin with, since it's mostly a side story to the Ecchi content and the romance.
It's a very dense mythology that unfortunately plays second string to a bunch of meh shounan content. Feel free to enjoy it all you want, but that doesn't suddenly make it great story telling.
Cast was large, but that doesn't make anime any bad. Each of the characters had his/her role, and very important one. And the plot is a great one as well. They could put together romance, ecchi, shounen, humor (an exceptional one) so neatly. I don't know anything about light novels, and I don't really care. Anime is so interesting it keeps me in suspense all the time. That's what i expect from a good show, and I get it.
Most of the cast isn't very important. And every one added means less screen time for the more integral cast.
The series has this huge mythology, and it spends most an inordinate amount of time on the Shounan class room stuff. It ends the first season with a ton of hints of more Shounan systems, and very little in the way of exploring the mythology more. I'm sure it'll get resolved eventually, but I imagine they're going to spend far more time on the gigantic breasts and resolving stock Shounan tropes like "collect all the doodads" than the structure of the setting.
