No one has ventured into the sixth layer of the Abyss and remained unchanged. No one returns from their Last Dive, and no one knows what happened to those who delved further. Even with the possession of a White Whistle, an ominous specter hovers above Riko, Reg, and Nanachi as they advance down to the sixth layer, the Capital of the Unreturned. The pathways are more treacherous, the environment harsher, and the creatures even more dangerous, but the...