"Shadow Beauty" follows Ae Jin, a high school girl who leads a double life. In school she's bullied by everyone and called ugly by her classmates, but in the internet she's a famous influencer named Genie, changing her appearance.

The first to know her true identity is Ho In. In the beginning I thought he was interested in Ae Jin and that was truth, but not romantically. The other is Ha Neul, she's Genie's best friend but at the same time, she's the person who's bullying Ae Jin.
There's also Mi Jin, a new girl who strangely is exactly like Genie. That was a part of the drama that I didn't like. I was expecting until the end that we find out that Mi Jin had done plastic surgery, because it's not realistic that a girl who looks like Genie appears, specially because Ae Jin made Genie, she's not real.

Ae Jin is a normal girl, but we live in a society that finds people's flaws and uses that against them, so Ae Jin thinks of herself as ugly. She makes a fake persona, because in that way she could have people's attention, being called beautiful for the time in her life, the problem is that her real and fake life keep crashing each other.
The message here is all about accepting yourself. To life your life in a way that makes yourself happy, not thinking about how others see you and also not to obsess over social media, because followers are not real friends, you need to appreciate the people that are around you and that physical beauty is really nothing if you don't have a good heart.