Who is SENA????

Her bestie from the original world who is also the novel's author where Lucia is stuck in.

Thanks. How did she get in the world. And why is she hiding. Maybe she doesn't recognize her friend because she looks different? Just me thinking out ouloud.

Apparently, the friend has always been somewhat jealous of Lucia?! (if I'm not wrong) and she made the manhwa where she portrayed herself as the female lead and made the villainess resemble Lucia. I don't know how she entered the story but I think she wanted to live her story as a reality(she was the first one to enter the book and that was intentional) but she didn't know that Lucia from the real world would end up getting in the book too. That's why she is hiding.

You may also check the old chapters where the friend was first introduced and she had a bizarre look during the scene, she was also saying that the scene is not playing according to her story. She is a strange woman.