It's not just mental. It's dancing like a maniac, waving pom-poms for "mental". It's a short-form series that's claiming to be split into four or five seasons (unclear), giving each one on average a shorter runtime than an ordinary anime episode... and yet this is sort of justified. You could probably make a full-length anime series out of a single Space Patrol Luluco "season". Its plot really does move that fast. It's a bit like the anime equivalent of Tharg's Future Shocks in 2000 AD, in which every four pages will have enough story for at least a month of a US comic book series.
This makes it hard to discuss this show without spoilers. It's not that the show doesn't have a format. It does. It's just that it doesn't stick to it. By the time you're halfway through, it's shed its first format and grown a new one. It then does a crossover tour of other Studio Trigger anime, dies, returns to life and generally does whatever the hell it likes.
This is thus going to be a short review, since there's not much I can discuss without spoilers. It's fun, though.
It begins with Luluco, who's a normal thirteen-year-old girl. She's proud of being normal. She thinks it's her finest point. If this show is about anything, it's deconstructing and reinventing Luluco's ideas of "normal". She lives with her dad in the Japanese city of Ogikubo (all normal so far), where humans and aliens live together and her schoolteacher looks like a cyclops in a happy green condom. Luluco's father works for the Space Patrol, where the chief of police is a living burning skeleton and all patrol officers can transform their bodies into guns. Imagine American gun fetishisation deliberately taken to its illogical extreme.
Meanwhile Luluco's absent mother is a space pirate called Lalaco Godspeed, while she has a turquoise-skinned classmate who's selling illegal Black Hole apps. (I still don't know what that means. Black Holes on your mobile phone?)
Luluco will keep trying to think of herself as normal, but this probably counts as heroism and/or madness. She is very cute, though. This is a Studio Trigger anime by Hiroyuki Imaishi, so it looks like Kill la Kill and has the same kind of cartoonish anti-realistic art. It's lovable. Look at Luluco's pointy bracket impersonation in the opening credits, for instance. Another thing the two shows have in common is the ability to draw sleazy outfits that somehow don't look sleazy at all, just as you wouldn't take offence at Jessica Rabbit.
This series takes almost no time to watch. Each episode is a third the length of regular anime episodes (and that's not allowing for opening and closing credits), so it's effectively a four-parter. Think of it as a concentrated version of itself. It's distilling the show you might have expected down to a high-energy, high-mental blast of fun and jokes. Midori is funny enough that you might wish she'd had more to do, but that's this show all over. You sneeze and it's finished. It's blasting through like this because it can. Give it a shot!