Wisteria is an orphan girl living a lonely life in the British Empire; she meets Marbas, an immortal being that is being hunted.

Wisteria is an orphan girl living in a corner of the British Empire at the end of the 19th century. Her life is desolate and bleak, until she encounters Malbus, a powerful but equally lonely immortal being with a furry appearance, hounded by hunters. Together, Wisteria and Malbus roam the Empire-populated by humans and human-like beasts in search of a place where they can live together in peace.

In Victorian England, the young orphan Wisteria begs for scraps. Able to see through demons' disguises, she befriends the immortal Marbas, lonely after centuries of solitude. He finds kinship with the human girl, even while evading the brutal Sword Cross Knights-including Wisteria's brother. Is it possible for two souls so different to find happiness together, and what price must they pay?—Crunchyroll