The Villainess in My Best Friend's Book

When Lin Yuan wakes up, she finds herself in a hospital. That's not the strangest part. Only later does she realize that this place is nothing like the world she knows. When she runs into Su Yunxi, she discovers that they have both entered the novel Su Yunxi wrote back when Lin Yuan made her angry that year. And that's not all: Lin Yuan has become the villain.

One day, the two of them find the notebook containing the novel and read what happens next. But the notebook is damaged, the plot goes off the rails, and everything changes. Strange people and strange events begin to appear.

Where will their fates lead in the end?

After they return to reality, is it really reality?

A note: There is no clearly defined male lead. Either of the two can be the male lead: one is from the book, and one transmigrates into it. But the story mainly focuses on Lin Yuan and Su Yunxi, and revolves around the two of them.