It's a bit of an odd one. It's an anime-original rather than an adaptation of something and I don't get the impression of a writer driven by the story he was telling. It feels more like an exploration of a world. Stuff happens in it. This TV series wanders around there. This can be exciting and I don't dislike the series at all, but I've no idea what might be in a hypothetical second season.

The show's most memorable aspect is a pink-haired girl called Kumi. She was being kept prisoner in a castle when she escaped in episode 1. She's an artificial being and she appears to make soldiers disintegrate. The show's strongest scenes involve her creation, alongside a platoon of Kumi-a-likes with scary personalities. (I'm reminded of Chaika the Coffin Princess, which was a better show.) These man-made experimental samples (i.e. pink-haired girls) shout at each other about being defective, why are you still alive, etc. Also, the scientists have soldiers who'll execute you for trying to help a girl escape.

That's just one bit of the show, though. We meet sardonic girls who wear magical cats, dogs, cows, lions and bears on their heads. Or indeed chickens. This makes them talk like their animal. There are paladins, one of whom quit his job in favour of getting drunk. There's a buxom herbalist called Romana. There are also the eponymous giant monsters, although they're just non-sentient wandering threats and not particularly interesting.

This isn't a bad series. It's just a patchwork that's hard to summarise. Also, I couldn't stop thinking of its title as Giant Beasts of Arse. (If you want to be even more juvenile, insert an "R" into "beasts".) I quite like the cast, though, and there's nothing wrong with these slightly jumbled but exciting story elements. I think the show's trying to be grand epic SF/fantasy of a kind the anime rarely makes these days, i.e. the world's bigger than the plotting. Commercially, this didn't work. It's tricky to sell a show to audiences when it's hard to describe it. The show was quickly forgotten, didn't generate buzz and didn't get people talking about it. That said, though, it's more ambitious than yet another copy-paste isekai, with some interesting worldbuilding and decent emotional beats. I couldn't tell you what this show was really about, but there's a fair amount here I liked.