2017 | 2 seasons | Japan
Located in the center of a remote island, the Abyss is the last unexplored region, a huge and treacherous fathomless hole inhabited by strange creatures where only the bravest adventurers descend in search of ancient relics. In the upper levels of the Abyss, Riko, a girl who dreams of becoming an explorer, stumbles upon a mysterious little boy.
