Bena

"Were you... thrown away, too?"

The Edo period. Circus sideshow worker Ichi is left in charge of the care and training of a beast captured to become the sideshow's next showpiece. Ferocious as well as ghastly, the beast terrifies all the caretakers; Ichi, already in a vulnerable position, was simply stuck with the task. At first he cared for the beast grudgingly, regarding it with a contempt born of his dark past experiences, but he begins to sense some humanity in the beast's actions and gives it a name – Bena. Bena's childlike innocence reminds Ichi of his deceased brother and, wanting to somehow return Bena home to his family, Ichi attempts to help him escape. But Bena is no human; he is a child of demons...

(Source: MangaPlaza)

Note: Includes four extra chapters.