It's fluffy, nice and funny. It's not dissimilar to shows like Komi Can't Communicate (although it doesn't reach that show's heights), except more deadpan and goofy. When I started, I was expecting an ensemble comedy with Aharen and Raidou merely at the middle of it... but no. It's almost all them. There's a small supporting cast, but hardly any of them matter. (Oushiro does, a bit).
AHAREN REINA is tiny, doll-like and apparently emotionless. She has only one facial expression and she can't judge distances, either physical or interpersonal. Her voice only varies from "semi-audible monotone" to "completely mute". This made her keep her distance from others and she had no friends in junior high school, bar Oushiro. You'd feel sorry for her if she weren't also a massive comedy goofball, and also if she didn't have...
RAIDOU MATSUBOSHI, who sits next to her in class and is about twice her height, but has a similar problem with expressing himself. He too has only one facial expression (except when ill). He's stoic, he's dim and he looks like a block of wood. He also has a crazy imagination that regularly convinces him of nonsense. Nonetheless, he was determined to make a friend on starting in high school and so he kept trying to be nice to Aharen, no matter how cold or bizarre her reactions.
They're perfect for each other. They're two halves of a whole. They'll both say, do and believe ridiculous things with completely straight faces, often not realising that anything's unusual. They're inseparable from ep.1 onwards and it's impossible to imagine either ending up with any other life partner.
Incidentally, you might be wondering if Aharen's tiny physique makes the show dodgy. She looks like a child. Is anime sexualising pseudo-children again? Answer (fortunately): no, I'd call it the opposite. Aharen's strange behaviour and actions could have made the show look sleazy if her body had matched her age. As it is, though, she looks like a child and dresses modestly (opaque tights under her skirt), so it's not a come-on when she drapes herself ridiculously on Raidou. Instead, she's just being a nuisance and it's funny. Also, neither of them seems to have even the slightest idea of sexuality (although the last few episodes are setting up a chaste romance between them, cheered on by their friends).
The supporting cast is largely negligible. The timid Oushiro is a meaningful character and I also liked our heroes' siblings, but Satou and Ichikawa are walking placeholders and I had absolutely no interest in their teachers. (Toubaru-sensei got a bit annoying, to be honest.) The arrogant brat Futaba was fun, though.
Basically, though, the show's just Raidou and Aharen being wacky with the straightest possible faces. Radiou will convince himself of something unbelievable on no evidence whatsoever, then immediately be proved wrong and say nothing about it. He challenges Aharen to games and duels that he takes super-seriously, but never wins. (Sometimes it's a tie.) One of the show's better jokes is Aharen and Raidou's tendency to have impassioned life-or-death battles at games at which they're both rubbish. Raidou's idea of a killer table tennis server, for instance, is... er, unimpressive. (Raidou also doesn't like losing, although he takes it gracefully.)
Occasionally, there's a bit of emotional depth. Aharen was lonely in junior high and she'd expected to be friendless again until Raidou came along. I'm fond of them both and I wish them the best as a couple. Basically, though, the show's an exercise in goofy deadpan comedy.