Do you think that Korea accepts gay people just because it produces BL dramas and movies? Wrong. They just make them because they are popular, and the audience is young girls anyway, who have two handsome male leads to drool over - or whatever may be those girls' reason for liking this content. I don't get it so I won't try to guess, although it's interesting from a sociological point of view.
But they wanted to target the more mainstream audience here, without the BL tag that would maybe drive away many viewers. So what did they do? A story of two gay boys liking each other wouldn't be acceptable, so they "magically" turned one of them into a girl, so it would be okay for them to date and be together, because they would be "straight". If that isn't homophobic as h***, I don't know what is. But of course a transgender lead would also not be accepted very easily, so... instead of hormones and butchery (oops, sorry, gender reassignment surgery), we have a super-handsome and kind fairy, who turns the boy into a girl overnight, without his knowledge or consent, just because of a mistake. How very convenient! And they went to great lengths to point out that the boy was desperate about this, he suffered, he didn't want it, it took him quite a while to accept it (so it wasn't a case of gender dysphoria before, thinking he was a girl in a boy's body or anything like that). That puts conservative minds to rest, so that they trustingly gulp down what follows.
I found it very manipulative, trying to sneakily push an agenda to traditionally minded viewers who are led to accept this sweet love story, so that then the makers of the drama can tell them "See? If you are okay with someone who turned into a girl by magic, why can't you be okay with it when it's done through the person's will and great effort? Isn't it the same thing? What's the difference?"
This apart, the screenplay makes water from everywhere. The deal the sister/agent makes with the athlete to come back to Korea, the girl who makes her whole family move to Korea to cling to her one-sided crush, the fact that neither family friends nor family (except for that one cousin: is she an orphan?) know or suspect anything about the sex change, the fairy's mistake (what was he trying to achieve with the spell anyway?) etc. Of course, what do you expect from a webtoon-based web drama? Ingmar Bergman?
This said, the actors were all likeable, good-looking and capable, you didn't cringe with their acting, as often happens with web dramas, they are to be commended. The whole quality was higher than of most web-dramas, that seem home-made and amateurish. They did put some serious effort here.
It was a short watch, but frankly I wouldn't recommend it.