It's a slice-of-life schoolgirl anime based on a four-panel gag manga. It's generic-seeming and pretty much the definition of harmless, but importantly it's also funny. I think it's a deceptively strong show, actually.
There's nothing special in the high school setting. It's all about the girls. These are:
1. WAKABA KOHASHI (waist-length dark purple hair)
She's the title character and the source of half the show's comedy. She's fabulously clueless. Her family is insanely rich and she's spent her whole life continually moving house because of her father's work. She thus knows nothing. She's almost completely ignorant about how the world works. Everything needs explaining to her, including basic things like "snow", "how to wear a swimsuit" and "how to eat takoyaki". She doesn't know what a mobile phone is. Taking her anywhere is like being the friend of a super-enthusiastic but unusually dim four-year-old, or perhaps an alien visiting Earth for the first time.
Her family have imposed a 6pm curfew, which seems a sensible response to the problem of letting this space case outside unsupervised. They're not much better, though. Asked for advice on where to take her friends for lunch, Wakaba's mother suggests France.
She's also an idiot. (Someone of normal intelligence could never be this hopeless.) However she's a lovely idiot. She's charming and likeable, even if her head's full of sunbeams. She'll get excited about anything she's never experienced before, i.e. everything. She's never had a friend before and she couldn't be happier and prouder of the three friends she makes here.
2. NAO MASHIBA, aka. SHIBA (grey/green hair plaited in pony tails)
The girl who talks like a boy. She'd like to be more feminine (although she's sensitive about being buxom), but she's also an otaku who plays boy-on-boy erotic computer games.
3. MOEKO TOKITA, aka. MOE (orange hair in big, fluffy pony tails)
The girliest of the four, good academically but hopeless at sports.
4. MAO KUROKAWA (pink hair with a couple of hair clips)
Sporty, but bad academically.
Nao, Mao and Moe (good luck telling those names apart) are obviously more straightforward characters than Wakaba, but that's okay. They work. Moe and Mao aren't very strongly distinguished, but they come across credibly. They seem like people in their own right, not collections of character traits and punchlines. They're nice to be with. They can also all be very funny and carry episodes on their own, mind you.
The show's also not exploitative. Wakaba and Shiba could both have been played for off-colour jokes, but this is a family-friendly show. There's no fanservice. There isn't even any lesbian subtext, which is unusual for a schoolgirl slice-of-life anime with no male characters and doubly so from the author of Kin-iro Mosaic. Indeed, Mao gets a crush on a boy we never meet, while Wakaba talks of getting married and having children.
It's a good show. It looked a bit generic at first glance, but it didn't take me long to decide that it was likeable, funny and had quite a lot of personality. Wakaba is a great engine for the comedy, but her friends are giving strong support too. It's nice.