Riko and Reg descended The Great Fault and met their fair share of troubles, but made it to the Goblet of Giants, the fourth layer of the abyss. An orb piercer ended up attacking Riko and Reg and poisoning Riko. Out of options, Reg was holding Riko and crying, telling her to breathe again. A curious visitor, Nanachi, was watching and helped Reg save Riko. Reg and Riko then lived with Nanachi for awhile and learned that Nanachi is a Hollow, as well as Nanachi’s friend, Mitty, who had lost all of her humanity and ability to speak. Nanachi and Mitty had previously been humans like Riko, but had been turned into Hollows when a sinister white whistle, Bondrewd, performed experiments on them in the sixth layer of the abyss, the Sea of Corpses. By pulling them up out of that layer, the strain of ascending made Mitty turn from a human into a mushy mess with one eye that can’t speak or do things humans can. Nanachi was affected as well, but to a lesser degree, and turned into a fuzzy creature kind of Hollow. Nanachi pleaded that Reg destroy Mitty for her with his incinerator move from his robot body. Reg eventually agreed to, but told Nanachi to keep living, even after Mitty is gone and Riko is fully healed. Nanachi agreed, and the three of them set out on an adventure back to where Nanachi came from, the bottom of the Abyss.