My little sister is the villainess, oh no, but so what?

That day, Count Blackthorn adopted a daughter into his family.The story of Zack Blackthorn and Cecilia Blackthorn begins then.

Zack: I have this status window thing... what a strange thing...

Cecilia: I've been reincarnated into the otome game, and as a villainess too? NOooo......!

[A/N: just wanted to write something fun on genre I've been interested in]