I Won Over the World-Destroying Villain [Book Transmigration]

Jian Jia transmigrates into a world teeming with mermaids and even gets a golden finger. It couldn't be better.

She has barely started enjoying herself when she discovers that she's actually transmigrated into a book!

The main story follows a Mary Sue heroine as she collects a harem, outsmarts the villain bent on destroying the world, and ultimately saves it.

As for Jian Jia, she's a cannon-fodder character who never really appears.

According to protagonist logic, as long as she stays away from the protagonists and the villain, she'll be safe and sound.

Jian Jia: Then that's settled!

But...

Villain: You belong to me in every lifetime. Where do you think you're going?

The male lead is ill, and seriously so.

Premise: