It's a 2019 harem comedy about a schoolboy (Futaro Uesugi) tutoring some pretty classmates. Yeah, like We Never Learn. I can actually enjoy good harem shows, but these two shows both fell off the harem cliff after a likeable beginning. The difference is that this show lasted longer.

We Never Learn's good start = episodes 1-4 (out of 28)

The Quintessential Quintuplets's good start = episodes 1-9 (out of 12, although another season's due in January 2021)

The non-harem side of the show is quite strong. Uesugi is a harem hero with a personality, which even mostly stays on the right side of "abrasive and possibly borderline autistic, but sympathetic". (Mostly.) His students have lots of different viewpoints and the show's still doing academic, non-romantic storylines even late in the season. Our heroes will be late to their examination halls and, startlingly, be sensible about Ichika's secret part-time job. (Yeah, the girls have made a promise... but priorities.)

Uesugi I liked. He's rude, insensitive and doing it for the money, but he's also honourable, reliable and serious about wanting to do a good job. He does care. He's always nice to his sister. Unfortunately, he does have a nasty habit of not listening to people and/or cutting dead an opportunity to be nice. His relationship with Itsuki is a multiple car crash. She meets him by accident at the start of ep.1, he's a jerk and she takes offence. Thereafter, the two of them are continually being cold and/or prickly to each other, with Itsuki being bloody-minded and Uesugi being a dick. (They thaw over time, but it's a case of four steps forward, three steps back.)

Of the other girls... Ichika is the self-appointed big sister, Nino would run a mile in spiked heels to sabotage the study sessions, Miku is a timid nerd about something amusing and Yotsuba is the world's nicest idiot. That's a dynamic cast. You could get a lot of stories out of them.

It's a good show. It's funny, including light, subtle gags that depend entirely on characterisation or good timing. I laughed at the "no, I'm not lying" sidelong look when Miku-as-Ichika is trying to praise Uesugi in ep.9. Unfortunately, it starts doing harem idiot plotting from ep.10 onwards. Uesugi pretends to be someone else in ep.10, then maintaining the lie even though his victim's fallen for this non-existent person and will be waiting for him at a school dance. There's a legend that a couple who hold hands at that dance will stay together for life, so of course it's taken deadly seriously. Uesugi gets locked in somewhere with one of the sisters and they don't just ring the bell to call security and get rescued, because we're watching dumb anime nonsense and it's assumed that another sister will overreact to this innocent circumstance.

One of the girls will eventually marry Uesugi and we don't know which one, ahahaha, quintuplets.

This harem cliff edge feels like a modern phenomenon, but does the memory cheat? Was I just lucky with the 1990s harem shows I watched? Ai Yori Aoshi, Hand Maid May, Tenchi Muyo and even something as ephemeral as Hanaukyo Maid Team: La Verite would still hold up if I rewatched them, I think, whereas Nisekoi, We Never Learn and The Quintessential Quintuplets all go downhill from a good start. (Tenchi Muyo eventually self-destructed, but it took ten years. There are definitely harem shows that don't stand up well to rewatching, though, e.g. Love Hina.)

Overall, I liked this show. I'd have been tempted by Season 2 if I'd thought the idiot harem plotting was a one-off. Unfortunately, I don't think it is. I think it's a mode. A previously good show will change gear into harem nonsense, because the romantic developments have reached that stage and it's only going to get worse thereafter.

Eps.1-9 of this are still good, though.