On her wedding day, Cosette Buisson is transformed into a demon by the'Malum' when her fiancée's soul is not properly reaped. But Cosette does not turn out to be any normal demon. She turns out to be a legendary demon called 'Dea'. When people start to notice her wandering around the outskirts of town, a rumor about a "Ghost Girl" begins to spread. When the rumor reaches the ears of Ciel Phantomhive, he becomes interested and seeks the Undertaker for information. When Ciel orders Sebastian to take her under his wing, will bonds be made? And will a broken heart find a way to beat once more?