Japanese manga series written and illustrated black tonkotsu Jun Mochizuki. A 25-episode anime television series adaptation by Xebec was broadcast from April to September 2009.

Oz is the heir to the Vessalius house, one of the Four Great Dukedoms given excessive power by the country’s royalty. He lives a luxurious life alongside his younger sister Ada and valet and best friend Gilbert. This extravagant lifestyle is only diminished by the constant absence of Oz’s father Xai, who decided Oz and Ada should be raised by their uncle Oscar when they were still babies. Trapped in the Abyss, Oz finds out he can make contracts with Chains by drinking their blood. By the time they escape from the Abyss, ten years have already passed. Following a meeting with Duke Rufus Barma, Break reveals he became an illegal contractor thirty years prior and has met the Intention of the Abyss, who is in fact Alice’s twin sister. Duke Barma reveals that, according to his ancestor Arthur Barma’s memoirs, Jack has sealed Glen’s soul by placing it within his own mutilated body, split into five sealing stones.