Operation: Saving the male leads

Yuki, after a sudden death, finds herself in the world of an ABO novel she read...as a character who doesn't exist in the original story.

Fem A x Male O

DISCLAIMER: English is not my first language, so there will be grammar mistakes.
I don't own the chinese novel "After the two pairs of families are divided into O ", I only own my Ocs, their plots and the AU part of this story.
The cover is not mine, I found it on internet so all the credits go to the creator.