Riko, Reg, and their new friend, Nanachi, continue their journey down the Abyss and arrive at the 5th layer. But in order for them to continue to the 6th layer, they must encounter the haunting figure of Nanachi's past: Bondrewd the Novel.
A girl named, Riko and her robot friend, Reg, journey down into a deadly, otherworldly chasm, known as the Abyss, in search of her lost mother.
After departing from Ozen's camp, Riko and Reg continue their journey, encountering more dangers as they descend further into the Abyss.