My Sister Who Regressed Wants My Fiance

Neris is forced into an engagement by her father, but when she arrives at the Duke's estate, her sister is already there, demanding the Duke for herself. As the Duke shows interest in Neris, she discovers her sister has returned from the past, determined to take everything—including her fiancé.

I got engaged on behalf of my sister.
It was an order from her father, who favored only her older sister. So she ran for a week and entered the public domain.
“Oh, are you coming now? Nereis.”
My older sister arrived first and greeted me.
She said, “I changed my mind. So you give in.”
Suddenly, her older sister covets the position of wife of the Ghost Duke.
“I like you.”
Regardless, there is even a peacock that only approaches me.
The incomprehensible situation did not end here.
Looking at my sister’s diary that I found by chance, it seems that her sister has regressed.
And that older sister, who has returned, covets my fiancé.