Kohaku no Silhouette

Liila gets a job as a servant at castle Aldevaran, which is rumored to be haunted and no doubt has a shady history. The Aldevaran lords have been known as cruel and thirsty for blood for generations. However, the current lord of the castle, Alferdo, is a gentle man. Normally one would think he'd be way beyond Liila's reach, but he looks after her. In time, Liila realizes she's in love with Alferdo, while mysterious and otherworldly things follow one another at the castle…

(Source: K.K. HarperCollins Japan)