Big Sister is Not a Bad Woman, She Just Loves Me Too Much

My name is Chu Ning, and I have transmigrated into a book.
I’ve become the evil older sister of the villainess Ning Yuan. The system wants me to bully her, humiliate her, and raise her darkening value to 95%?
But I was a man before I transmigrated.
I have no interest in female rivalry, and I’m terrible at acting as well!
Seeing my sweet and soft little sister, all I want to do is give her pocket money, pinch her cheeks, and praise her for being amazing!
The system says that if I fail the mission, I’ll die in six months and become a wandering ghost.
To survive, I have no choice but to suppress my conscience and ruthlessly bully her.
Finally, her darkening value skyrocketed, and my life is saved!
But why does the way she look at me become increasingly… obsessed?
—
My name is Ning Yuan, and my world keeps resetting because of a fool named Chu Ning.
Every time a reset happens, Chu Ning will be replaced by another person.
Every Chu Ning has been verbally abusive, even physically violent toward me.
So I killed them all.
This is my thirty-first reset, and she is the thirty-first Chu Ning I’ve met.
Just when I thought she wouldn’t be any different from the others, she handed me a chocolate ice cream I never tried before and told me to follow her.
Is she really different from the others?
Even though she still bullies me, it’s the kind of bullying that I can’t resist at all…
I want to keep her, to make her stay with me forever!