Transmigrate into Seer and Become Blake's Younger Sister

Black and the original heroine, Brianne, are the main couple.

After dying, she is brought by a System into the world of Seer, where she and her childhood idol Black find their way to each other and live happily ever after. The whole story is sweet and romantic, with no angst.

The System that brought Brianne to this world has a story of its own, and Brianne slowly helps it heal, too.

This is my first time writing a book, so please forgive any shortcomings.