During Reg's first descent, he and Nat come across a Praying Skeleton. Reg, unprepared for the sight, freaks out, but Nat, amused by Reg's reaction, tells Reg about the Birthday Death Disease, hoping to scare him further. Instead, this only increases Reg's resolve to enter The Abyss and find the answers to several mysteries. Nat becomes very angry, and insists that Reg and Riko are crazy for wanting to do something so dangerous.
On the previous night, Riko shared the message found in her mother's letter with her friends. Riko is convinced that Lyza is asking Riko to find her in The Abyss, and Riko is determined to do so. Nat is firmly against Riko's plan to leave. He reminds her how dangerous it is, how unprepared she is, and all that she would leave them behind (namely, she would never see her friends again). Riko refuses to be swayed, and ends up fighting Nat in her frustration. Shiggy volunteers to help by obtaining more information for Riko. Reg, concerned by the tension between Riko and Nat, wonders how things will work out.
After Reg's first descent ends, he is distracted because his memory didn't return as he'd hoped. He completely misses that Nat is lagging behind, suffering from 1st layer ascension strains, until Nat vomits. As Reg has his artifacts appraised, he recognizes that the Curse had no impact on him, and wonders if he truly is the figure described in Lyza's letter. Overcome with the desire to know more about himself, he decides that he must act.
That night, Riko tells her friends that she will leave the following day, just before dawn. When Shiggy asks how she will enter The Abyss, Reg volunteers to lower her with his extending arms, and announces he will go with her, both to find his own answers and to protect her. Riko is overjoyed. Shiggy is more practical, calling their overly optimistic approach naive. He brings out the latest Abyss depth chart, describing each layer and its dangers in detail. He notes that if a Red Whistle reaches the 2nd layer, it is treated as a suicide, and search parties will not pursue them any longer. Nat tries again to talk Riko out of going, but she stubbornly refuses, until Nat finally blurts out that no one could survive for a decade in the Abyss, and that Lyza must be long dead. Kiyui bursts into tears while Reg tries to comfort him, Riko runs out of the room, and Nat is left feeling guilty.
As Riko and Reg prepare to leave the orphanage, Reg suggests that Riko make up with Nat. She refuses, until Reg points out that they will never see Nat again. Riko agrees to forgive Nat if he apologizes. Shiggy will accompany the pair as far as the edge of the Abyss. Reg says goodbye to Kiyui, whose birthday is near, so Reg gives him some advice on avoiding the Birthday Death Disease. Reg then runs into Leader, who is patrolling and already knows that Riko is missing. Despite Reg's obvious nervousness at being caught, Leader lets him leave. Reg goes to Nat's room, but the bed is empty.
Riko, Reg, and Shiggy meet up in the South District. Shiggy advises them to enter “The Abyss” through the entry point at the wharf slums, which are not monitored as closely. He has already gotten someone familiar with the area to lead them, which turns out to be Nat. Nat apologizes to Riko, who instantly forgives him. She believes he has finally come around, but Nat makes it clear: he is willing to help her, but is still against her leaving. Reg says they will send Nat letters, but Nat disagrees, pointing out that the likelihood of mail reaching the surface from the depths is very low. Riko promises to write many letters, so that at least some will reach them. Nat explains that the wharf was built by illegal delvers, and that he and his late sister used to live there. He dreams of becoming a Moon Whistle, and returning to build an orphanage there. Riko encourages his dream.
The group soon reaches the edge of The Abyss. Reg then notices that there is a letter from Leader mixed in with their pack, but doesn't mention it yet. As the group says their goodbyes, Nat struggles to tell Riko how he really feels, but can't. They are both in tears, and Riko says they will be forever connected by The Abyss. Realizing that they have disturbed the residents and are drawing attention, Reg and Riko quickly descend into The Abyss while Shiggy and Nat watch.
- Volume 1, Chapter 6: Premonition
- Volume 1, Chapter 7: Eve of Departure
- Volume 1, Chapter 8: Here we go!
references to previous episodes