Moto Oshi no Hisho ni Narimashita

Being reincarnated into a novel as your favorite character's secretary sounds like a dream come true, but when Mia Lisicha experiences exactly that, it's different from what she expected. Grand Duke Asad Ulriel is far more ruthless than he was in the novel, and Mia finds herself unfairly imprisoned in his manor. Undeterred, she immediately begins plotting her escape but is quickly caught by the grand duke. Can Mia prove her innocence, or will meeting her hero turn out to be her biggest regret? (Source: Tapas)