Izuku Midoriya is going to superhero school! He wasn't born with superpowers, unlike 80% of people these days in the entire world... hang on. Whoah, no no no, just a second. How come we're not flying to the moon, living in cloud cities, abandoning fossil fuels, etc? Society still looks pretty normal. Hmmm. Let's put that aside for now. What happens this season?
Short answer: Midoriya and his classmates will have to study at school, compete in sports festivals, do unpaid work experience, avoid getting murdered by the Hero Killer and survive the "decay on touch" hands of Tomura Shigaraki!
Slightly longer answer: they'll fight quite a lot, because this is a shounen series, but this isn't a macho series (despite the best efforts of loons like Bakugo) and most of it is in a controlled academic environment. This season has 25 episodes, which can be divided almost exactly into quarters.
PARTS 1-2: welcome to the Sports Festival! It's a student knockout tournament that's televised with the entire country watching, including all the hero agencies. The best-performing students might even get job offers.
PART 3: work experience! Our heroes become unpaid interns, to learn more about the real world and (in some cases) discover that they should have thought a bit more deeply when choosing their placements. Midoriya joins up with Gran Torino, who you can imagine as a superpowered cross between Yoda and Clint Eastwood, but played for comedy. Uraraka makes an apparently uncharacteristic choice. Bakugo will make you laugh a lot. Frog Girl (okay, Froppy) gets a spotlight anime-only episode, to make up for getting disgracefully little time in the spotlight in the regular manga-based episodes. (Frog Girl rules.)
There's also proper supervillain action. This tends to be scarier and more dangerous than our school-age heroes can handle on their own, partly because they're not good enough to turn professional yet and partly just because this show has serious supervillains. We glimpsed Hero Killer at work in Part 2, but here our heroes aren't even at school any more. If you meet him and get hospitalised, you got off lightly.
PART 4: back to school for the practical exams. This is teachers vs. students, although the teachers fight with handicaps and there are always two students working together against any one teacher.
It's good stuff. I always enjoyed returning to this show. Heroes like Midoriya, Uraraka, Frog Girl and many others are terribly likeable, while the more obnoxious ones are still interesting. Bakugo is fascinating, I think. He's such a quick-tempered ball of psychotic rage that it's impossible not to think him an idiot, but he's also a classical shounen action hero in a mild-mannered series that's both mocking him and taking him seriously. (He's also often hilarious.) There are character-based storylines, with quite a few students having damaging emotional issues. They don't all manage to get over that, either.
That said, though, I'm not sure it's at its best if you marathon it. School tournaments don't really matter, after all. Every episode is great fun and very likeable, but I don't know if I'd call this a story-driven season. I think I preferred Season 1. That said, though, I did a fair bit of marathoning and still very much enjoyed the show, so by all means go for it if the urge takes you.
The show's Japanese take on superheroes is getting ever more interesting, even if it's not the focus of the show. I was wondering earlier why this majority-superhero civilisation looked the same as ours, to which the answer might be "oppressive regulation". Superheroes need a licence and are employed by the government. Effectively, they're civil servants. They don't even have the authority to arrest or punish evildoers, which sounds crazy at first glance. What do you do? Tie a rope around your enemy and take him to the police? Answer: yes, I think that's exactly it, but that's not the end of it. Defeat a supervillain while you're still a school student and you might get punished for doing so. What the hell? The guy was going to murder everyone! You saved them (and yourself). What's so bad about that? That's a topsy-turvy law that makes no sense, but that fits in this society where the published facts might be censored and the public won't necessarily know what really happened. That dog-headed police chief in ep.31 calls it a "climate of suppression".
It doesn't look that way, mind you. It looks like a nice, normal superhero show with lots of nice school-age heroes. Dig beneath the surface, though, and that's what you'll find.
I also admire the nature of Midoriya's powers, by the way. It's obligatory in this genre for the protagonist to keep getting stronger. In this case, Midoriya has had the world's greatest superpower almost since the beginning, but what he lacks is the ability to control it. If he throws a punch at 100%, he'll turn his own bones to jelly. Even operating at 5% would hospitalise him if he made a mistake, which he does regularly. This is both a great source of story material and a natural way to let him progress as time goes on.
This show is an easy recommendation. It's got a huge cast and you're sure to find lots of characters you like, although the show also keeps an intelligent focus on the ones it thinks are most important. There's a terrifying supervillain on his way. (He hasn't arrived yet, but it won't be pretty when he does.) It has cool stuff like the episode where at last you see the headmaster in action. This is awesome because he's such an unlikely superhero. He's an adorable talking mouse who barely comes up to your waist and looks as threatening as a bunch of daffodils. (This is misleading. Yowzers.) This show is a big hit. Both the manga and the anime are clearly going to run for years and years, but with the twist that the anime's rationing itself to a limited number of episodes a year, to keep up the quality of both the storytelling (no filler episodes) and the animation (which is far better than most long-running shounen shows). Sounds good to me. Give it a go.