The Abandoned Duke's Daughter Is a Hikikomori in the Forest

Synopsis

I've been kicked out, I'm going to live happily in a chicken coop!

Chloe, a simple duchess with a grimoire, has her engagement broken by the crown prince through her sister's tricks, and everything is taken away from her!
Chloe is cast out and retreats to the forest, but the Book of Black is indeed the most powerful of all the grimoires!
I don't have to pretend to be sober anymore, do I?
Chloe uses her power to have fun with the magical beasts.
However, the situation changes when the magical knight Ernesto shows up!
He says that Chloe once tried to kill him, and suddenly says, "If she is a bad witch, I will kill her." ...?