It's a next-generation anime romantic comedy... someone's invented "sado-dere". Time for a quick Japanese lesson! (Note: these words have other meanings too, but what's here are the relevant ones.)
TSUN-TSUN = prickly, grumpy, hostile, stand-offish
DERE-DERE = lovestruck, fawning
TSUNDERE = portmanteau word to describe someone who's both tsun-tsun and dere-dere. They're everywhere in anime. They've been here for years. The most common kind of tsundere is obnoxious, but with a hidden loving side. It usually grows over time, thanks to character development and "aww, they love each other underneath".
SADO = sadism.
SADO-DERE = a sadistic tsundere variant who teases and bullies her victim.
Welcome to Miss Nagatoro.
Unsurprisingly, this isn't universally popular. Plenty of people bounced hard off this show, often the same people who disliked Uzaki-chan Wants to Hang Out!. (Both are romantic comedies about a hot girl who fixates on and mercilessly pesters a solitude-loving senpai with minimal social skills.)
I love both, personally, although I don't like all such shows. I dropped Teasing Master Takagi-san, for instance. What's more, Uzaki and Nagatoro are similar enough that they're worth comparing.
The character dynamics are different. Uzaki's Sakurai was bigger, tougher and ruder. Nagatoro's victim, on the other hand, is a dork who'd been heading for loser loneliness. He's got the spine of a jellyfish and an endless supply of outraged faces. He had no idea how badly he needed help. He just wanted to be left alone, but doing so wouldn't have been kindness. Nagatoro compares him to maggots, sheep and wharf roaches. Theoretically, his dialogue is as tough and blunt as Sakurai's, but from him it sounds silly and everyone laughs at him.
Nagatoro, on the other hand, is a cat with a mouse. She plays with Senpai. She'll do anything to horrify him. She makes him cry twice in the first episode... but, over time, certain things become clear. With him, she's hyper and having the time of her life. With other boys, she's bored and hostile. She spends all her time with him. She gets annoyed if you say she's not Senpai's girlfriend. She gets possessive and will defend him from others (e.g. her trouble-loving friends). She tries to improve him, e.g. taking him on runs for physical training. She supports his interests (art), even though hers are completely different (sports).
She'll often say or do risque things, because those get the most extreme reaction from him. This tends to go wrong and embarrass her too. Underneath the teasing, she'll be blushing just as much.
It's a good show to binge, because you can follow the character development. You see Nagatoro's non-reaction to other boys and her defence of Senpai. In ep.5, they're swapping contact details for the summer holiday. The question on their minds in ep.7 is whether he should have invited her to the summer festival. It's become an outright romance by the time we reach the finale. There's a second season coming and I'm a little nervous, because I wonder if the show will hit a reset button to keep the formula going. (If the relationship keeps developing this fast, they'll be married by their high school graduation.)
I wouldn't recommend that kind of relationship, obviously. Nagatoro needs to drop the mask. She's essentially a tsundere, i.e. in real life she'd be tiresome. (Japan has tsundere cafes, where the waitresses say, "I don't care what you order and I didn't want to bring your food anyway." Gyaaah.) For me, though, with these specific characters, this show works.
To widespread surprise, this was one of the biggest hits of the Spring 2021 season. Also, the animation's great, with a ton of character in the faces. I can even forgive the silly challenge for dramatic contrivance in the last few episodes. It's lovable. (In my opinion, anyway. But not everyone agrees.)