Hakushaku to yousei, book 2: Amai wana ni ha ki wo tsuketeMizue Tani2004

Lydia is a girl who can see fairies and was hired as advisor to the Earl Edgar (but former thief?!) and now commutes to work at his manor. One day as she's seduced by Edgar, who makes advances on her whenever he opens his mouth, she is nearly abducted by a giant malicious man resembling a fogman in the park. After managing to safely return to the manor, Lydia happens to be visited by a female visitor. After listening to the woman's story, it turns out that a young Baroness may have been kidnapped by the fogman...!?