Nanachi and Mitty's past is revealed. How did they become what they are and who is responsible for it? Meanwhile, Riko is on the mend after her injuries.

Reg and Riko run into trouble deep in the fourth layer where they meet an interesting creature, but are they friend or foe?

The reckoning comes, but Reg is too kind and foolish to be a bystander.

In the end, everything comes full circle.

The village’s membrane has been breached, and through the gap floods chaos itself. But as attackers enter from without, aid comes from within.

Nanachi shows Reg the truth about the Abyss. Meanwhile, Riko is still recovering from her injuries when she has a strange dream.

Ozen tasks Riko and Reg to survive alone outside the Seeker Camp. Do they come out alive and unscathed? Or does the Abyss have a dirty trick up its sleeve?

They had their reasons for descending into that infernal pit. They found damnation and salvation in equal measure.

Riko, Reg and Nanachi take their first steps into the sixth layer. Both wonders and dangers await the trio, but they are unaware they are being watched.

Riko and Reg start their adventure into the Abyss, while there they run into an unexpected familiar face.

Reg goes on his first cave raid! Meanwhile, Riko makes preparations to go into the abyss to find her mother.

The villagers must lure abyssal fauna into the village to hunt them. But when one creature proves too much to handle, Riko needs to help the villagers defend their home.

An old man speaks of a golden city that lies within a devouring abyss somewhere in uncharted waters. One explorer may be the key to finding both.

Reg and Riko make it to the Seeker Camp where they meet Ozen the Immovable, the person who saved Riko all those years ago. But there is more to Ozen than meets the eye.

Some say there’s a secret hidden deep within the dark cave at the edge of the village. Villagers don’t investigate and stay far away, but Riko isn’t a villager.

Riko and Reg find out more about their past but the question still remains, who or what exactly is Reg?