So, Let's Nupu Nupu wants to be a raunchy Adult Swim-type comedy, which isn't necessarily bad... but it's all lech humour with a side of nonce. The jokes are also very simple and nuance-less, so if you think a teacher assaulting and sexually harassing a child is funny, they do that about 20 times. About halfway through the show, she burst through the roof of the boy's dentist appointment and tried to drool in his open mouth, and from then on I just really wanted it to end. Basically, this anime is just 'adult' humour in the lowest common denominator kinda way. Every other joke boilsdown to haha sex/haha sex pest and the rest aren't even memorable enough to offset this. You can tell where most of these bits are going to go from the moment the characters show up onscreen. Seriously, it's to the point where when I see that some new characters are a pair of siblings, I immediately expect their entire bit to be incest. And of course, it is.

I'd discuss the other recurring segments, but I don't have much to say about them. Sushi Cat appears to be Let's Nupu Nupu's attempt to make a mascot character, but his bits are rather directionless and change completely every few episodes, leaving him rather bland -- the nurse and student end up far more emblematic of the show. There's a hamster who disappears after like 2 episodes never to be seen again, and a teacher of young children who appears in the last like 3 episodes. Otherwise, every other recurring segment revolves around the aforementioned sex jokes.

Overall, it's far from the worst anime I've seen, but I spent far too much of the runtime wishing for it to end or wishing for a bit to be over to say anything nice about it.

P.S.: The nonce nurse might still actually be better than Marimo, who's entire gag is she's a little kid who magically turns into an adult and then her clothes get tight and she gets off to that.