All 13 episodes of the Japanese anime based on the manga series by Akihito Tsukushi. The show follows orphan Riko (voice of Miyu Tomita) as she descends deep into the Abyss with her android friend Reg (Mariya Ise) in search of her mother. The episodes are: 'The City of the Great Pit', 'Resurrection Festival', 'Departure', 'The Edge of the Abyss', 'Incinerator', 'Seeker Camp', 'The Unmovable Sovereign', 'Survival Training', 'The Great Fault', 'Poison and the Curse', 'Nanachi', 'The True Nature of the Curse' and 'The Challengers'.