That's is the best resume one can give about the story. I'm not going to lie, it has a lot of pet play, characters being hurt, characters crying, animal abuse (so if that's a trigger, even just discussed, you should stay away), child abuse, neglect, lots of violence... Also, the violence happens mostly between girls, so if you have a romanticized vision of women's relationships or that women=good, you might not like it.

First we begin with Gayoon! She's a cutie who looks like a dog. More specifically, like Soha's dog. She makes funny faces often, she's cheery and always want to help her friends, and she's a spineless doormat. She can't fight to save her life. And that's what makes her vulnerable to Yurim, the bully since the beginning.

Then we have Soha! The pretty handsome girl, super cool, that hates bullies! Because she used to look the other way when her dog Happy

Spoiler, click to view

(remember the animal abuse i mentioned?) was abused physically by her older brother.
For a dog with such a name, it didn't turn out very happy.

The dog wasn't stupid and ran away,

Spoiler, click to view

but for a long while I had the impression the big brother could have killed the dog lololol ;w; but everyone insists it ran away, so i guess so. Soha since then learnt to fight and defend herself, and see her brother on the bullies of her school.

Specially when Yurim decides to bully Gayoon right where Soha can see them, because Gayoon looks like a dog.

Gayoon also makes friends! With a girl called Sol (who's very baby butch looking, very popular, many girls get all sapphic over her and don't even question if she's sapphic as well lmao) and a younger girl called Soo, who's head over heels for Sol and gets all shy and quiet when around her. Gayoon gets to make them become a couple way before Gayoon herself gets to a relationship, and that kills Gayoon a bit.

But anyway! Pet play.
Because Gayoon looks a lot like Soha's dog, she offers to be her dog, like roleplaying. but. but. It's pretty lewd, not gonna lie.
Gayoon wears a collar, that has a leash, she licks Soha, she bites Soha (and leaves many bite marks that look like hickeys). They snuggle cutely on the bed and the sofa, sharing candy.
Soha punishes Gayoon for biting so much with an electrical collar that malfunctions and probably traumatizes them both, and gives her a muzzle.
Also they go out in the park to play catch until Gayoon is spitting out her lungs.
To be honest, the first time I heard of this story was a meme using Soo's finding of the collar and realizing it was used on Gayoon by Soha. haha

The problem though is, Soha lacks memories of when she saved Gayoon the first time, because she was in a big hard time

Spoiler, click to view

(with her brother and with Happy gone).

So everything Soha does to Gayoon, despite how lewd it looks, is Soha seeing Gayoon as Happy.
And after a while, it while not exactly enough for Gayoon, ends up hurting her. Because Gayoon wants to be closer, but she can only be closer as Happy, not Gayoon, and none of the two can help Soha out of all the trauma she's going through. And when it comes out that even the first time Soha saved Gayoon, it was because she saw her as her dog... Ooof. Gayoon felt like she was nothing to Soha. And she goes through some dehumanization pretty heavily, by her own feelings of the situation, by Soha's good intentions and trauma coping and also by Yurim's bullying.

Oh yea! Yurim comes back to bully. There's a lot of crying, a lot of beating up, so if you aren't a fan, maybe you will have a hard time reading? Yurim have a really sad backstory, but it's like Soha said by the end. She went so far, it's hard for Soha to feel apologetic about it. It's so fucked up though.

Spoiler, click to view

An asshole girl makes Yurim's frustration all about her, in a way that is too far.
Yes, Yurim pushed and screamed at her for making it all about her. Then that girl decides to ask the bullies to give her a lesson and thinks that will make them even and turn them into "friends" again. Yurim gets slapped a lot because she's not supposed to hurt people outside of the boxing, and then gets bullied the rest of the year. The closer friends said a lot about how she should be angry about it, as if she isn't, but what is she going to do? It was hurting people outside of boxing that began it all. And then a girl is forced to push Yurim, almost kills Yurim, and then Yurim is full of that shit rightfully and beats up the bullies.
Remember the asshole girl? She comes to tell Yurim how she felt oh so bad about it all, and how she didn't want all of that. You know, like a child steals an apple and you call a child abuser to solve the problem and don't expect the child to be abused. Yurim gets pissed off, Soha appears before she can beat the asshole girl into a pulp and ruins any chance of Yurim to go back to a happier self.

You see, Soha is very insensitive. She also grows more insensitive. So she says the worst thing at the time, and marks Yurim as her rival. Yurim begins to bully a lot of kids, including the asshole, until she reaches Gayoon.

That forces Soha to fix what she did and failed to do in the past. Like a fair fight.

Oh, don't worry, there's lots of romance! It's just that we get lots of angst too, in a whumping way or not. There isn't that many flashbacks, but there's some. Also Horang probably liked Soha, but she's fine with Gayoon bringing Soha's smile back.
Gotta love how the teachers have no fucks to give. But I mean, isn't that just like most schools are? haha It also calls out how schools in Korea and other eastern countries can be about bullying. Sure wish many western ones didn't go in the same way too. Physical bullying happens a lot in the story.

If you dislike (or are triggered with) violence, bullying, kinky stuff, girls being horrible to each other, the reminder that kids can be horrible, the deep neglectful nature of all teachers, girls being bashed into pulps and domestic abuse, this might not be the comic for you. It's easier if you enjoy reading about some of those, because you will see that a lot, and disliking it but reading anyway just means you are upsetting yourself. Those scenes happen a lot and there's character development through some of them. I keep saying that because sometimes people cry about it.
Also yea, I'm pretty sure the artist is a man. I'm amazed at how he wrote girls' worst selfs so accurate. I really hope it's not from personal experience. He deserves the best for gifting us all with Her Pet.
This is not the comic you read to feel good. It ends well and wholesome, but the way to it is not wholesome at all. I love the story, the art, the characters and their arcs, and all its happenings, and I love how not-wholesome it gets. For a spineless weak girl, Gayoon does her best and influences people to find happiness eventually, even if she gets beaten up in the process. She's also fuccin adorable.