It's the Studio Trigger hit show that won back the crowd after they slipped with Darling in the Franxx. It's also, bizarrely, an anime sequel to a live-action tokusatsu show called Gridman the Hyper Agent, adapted in America as Superhuman Samurai Syber-Squad. (Tim Curry played a villain in it.)
The original Gridman was a vaguely Ultraman-like superhero (and interdimensional police officer) who fought giant kaijuu. He lived in computer games or something. I've never seen it, but I believe it was pretty popular and this isn't even Studio Trigger's first anime adaptation of it. They also revisited it in a 2015 Japan Animator Expo short. Personally, I was neutral about all this. This isn't my favourite genre, but I like Studio Trigger. Fortunately, the show's excellent. It's as if their mission statement was to take a repetitive kiddie formula and show us how to make it thoughtful, surprising and interesting.
Firstly, the "repetitive" thing. Gridman fights big dumb kaijuu. That's what the show's built around, both the original and this new version. Smash up the city! The next day, no one's noticed! Do the same thing every episode! You might be wondering why we should give a damn about meaningless fight scenes against lots of monsters of the week... well, this anime makes it work. Firstly, the show's aware of its genre peculiarities. Our heroes freak out a bit when everything's back to normal the next day and no one remembers. (This includes the friends and family of people who got killed.) There will be an explanation for this and it's not what you're imagining.
More importantly, though, the show has a kaijuu-making villain who's such a fascinating, messed-up character that she appeared on reviewers' lists of "best anime character of the year". Her name's Akane. The kaijuu don't matter in themselves, but they're Akane's weapon against the world. The show keeps making us change our opinion of Akane, from cute schoolgirl to casual psychopath to a bunch of stuff that it would be a crime to spoil. She's an otaku who lives among garbage and action figures. She wants to get close to people, but she's a walking empathy failure and she might arrange your death for bumping into her in the corridor. She's usually cooped up in her front room in front of a screen, making kaijuu models. She's the dark side of ourselves when it comes to technology, computers, smartphones, TV shows and other things that can distance you from the real world, being a huge fangirl about exciting kaijuu fight scenes and not bothered in the slightest about the death toll. (Kaijuu can knock down buildings just by stepping backwards. They have laser breath and superpowers. The show knows that this is super-cool, but also that it's horrifying.)
That's only a fraction of what I could say about Akane, by the way. I'm dodging spoilers. She and her pain almost become the show's main character. The lines between hero, villain and monster are being blurred and played with. Surprising groups of people go to a Chinese restaurant together. Ep.6 has all three heroes hanging out with a villain. Kaijuu are monsters, not people... except when that's not true.
The heroes are less attention-grabbing than Akane, but they're still likeable and easily capable of carrying the show. Yuta Hibiki is a nice schoolboy who wakes up with amnesia in ep.1 and has a mysterious link with Gridman. Rikka Takarada is a calm, mature schoolgirl whose mother owns Gridman's computer. (It's in their junk shop.) Sho Utsumi is a fairly cool fanboy in glasses who loves kaijuu and fancies Akane. They're living in a Twilight Zone reality where a supervillain sits next to Yuta at school and where one might regularly have to transform into a thirty-foot-tall Power Ranger and fight monsters. They manage pretty well with this, I think. They keep the show engaging and real.
That said, though, not everyone thinks the show is flawless. Things that might rub you up the wrong way include:
1. THE FANSERVICE
Akane wears her jacket in an off-the-shoulder style that frames her boobs. Rikka's loose jacket tends to hide her short skirt, making her look as if she's forgotten her trousers. Those two girls have a lot of fans and hence also serious-minded critics.
That said, though, this is pretty mild fanservice and I think some people have been getting overexcited. The girls do look sexy, especially Rikka, but it's "normal person walking down the street" sexy rather than actual nudity. Ep.5 is a swimsuit episode and that's pretty much it. Akane's top isn't figure-hugging at all and you'd hardly know she was buxom if it weren't for ep.5.
2. THE FIGHT SCENES
The script might be clever, witty and surprising, but it's still based around campy monster-of-the-week fight scenes. The show's fundamental assumption is that THAT'S AWESOME!!!, but not everyone will agree. (I don't, for one, but personally I thought they were okay. I like camp and they didn't drag on too long. That said, though, it's noticeable that, say, the one in ep.4 demonstrates that such fights are normally a bit rubbish by breaking the rules and being good. That one's personal for both sides.)
3. THE UFO OVER THE CITY IN EPISODE SEVEN
If you saw a UFO flying overhead, what would you do? Gridman immediately shoots it. I fell about laughing. (As it happens, his judgement was correct and he hasn't just doomed the human race, but only because he happens to be in this genre and no other.)
It's a cool, intriguing show. It's doing clever things with what's usually a dumb genre. It's camp, funny and absurd, but also sinister and constantly getting darker. It has so many layers, in fact, that the last few episodes have largely gone beyond traditional "hero vs. villain" adventure and might not be as satisfying if you're just looking for a Hollywood action finale. (There's still kaijuu-punching, of course, but that's just one layer of what's going on.) It gets psychologically intense. It's got depression, loneliness and what looked a lot like attempted suicide. Definitely one of the more interesting anime of the year.