The Good-Times Montage in Episode 2 has Reg easily integrating himself into daily life at the Belchero Orphanage and developing his relationship with Riko. There's a shot where Riko and Reg sleep together in the same bed, and it's utterly adorable.
Lyza the Annihilator abandoned her mission to retrieve the Unheard Bell, leaving behind the special-grade relic, her reputation as a cave raider, and the corpses of her subordinates, friends, and husband just to bring a newborn Riko back to the surface in an burdensome Curse-Repelling Vessel. Mind you, once she was safely on the surface Lyza went back into the Abyss and completed the mission all by her lonesome, but she still prioritized her daughter and ensured that bad eyesight was the only issue Riko had coming up from the Fourth Layer.
Reg takes time out of his escape the orphanage to give a last farewell to Kiyui. On a related note, Riko finally manages to leave everyone at Orth on good terms and without regrets, especially after a nasty argument she had with Nat earlier.
In the fourth episode of Marulk's Daily Life, the eponymous character wakes up from a dream of how he got in the Abyss to begin with. The airship he was in crashed in the second layer. His father and the rest of the crew died from the incident. Marulk was the only survivor and thought he was also gonna be a goner... until Ozen found him and carried the boy to safety when he fell unconscious when he showed signs of wanting help. Marulk wakes up with a tear on his eye to see Ozen looming over. Surprised, he apologizes for having slept, but Ozen doesn't seem to mind. In a highly rare moment of genuine painless physical affection, she pokes his cheek. Ozen teasingly asks if he had a scary nightmare with her usual trollish grin. She soon drops the smile when Marulk affirms in seriousness, whether in surprise or concern. As Marulk says in the end, it was scary, but bittersweet.
Nat hopes to open an orphanage in the Wharf, so that other children like him will have a chance to become cave divers and escape a death condemned to the slums.
Riko spent her entire time unconscious on the Fourth Layer comforting Mitty despite her own mental suffering. Then, once Reg performed a Mercy Kill, Mitty's soul guided Riko back to waking up.
Nanachi's form and retaining their consciousness are due to Mitty's desire to protect them while being cursed. Even when the girl was begging to be killed as the Curse tore her apart, she still managed to maintain an incredibly powerful will out of her love for Nanachi.
The bath scene in Chapter 25 / Episode 13. It's somewhat Played for Laughs, but after the anguish of seeing Riko nearly die and then seeing Reg put Mitty out of her misery, it's still heartwarming to see signs of affection and love in the midst of horror.
Sometime after the bath, Reg is lamenting that Riko has a rather massive scar on her arm because of his botched attempt at amputating it. but Riko tells him that her scar is proof that Reg protected her, giving him an affectionate headbutt as she says so. D'aaaw!
Meanwhile, Nanachi is standing further away from them, watching them and covering their face with their ears as if to say, "You two areway too adorable."
Speaking of Nanachi, them agreeing to join Riko and Reg on their journey, in part as thanks to them for caring for Mitty. (That, and Riko's delicious food.)
The ending montage of the anime. It shows Riko, Reg, and Nanachi preparing for the next step on their journey, such as gathering tools, helping Riko rehabilitate her arm, and so-on. The cherry on top, though, is that the three send a hot-air balloon to the surface. Early on, it was stated that very few messages sent via air balloons made it to the surface as they'd often get destroyed or caught up in the Abyss by the creatures or flora. Despite that, their message reaches all the way up to the surface, after enduring the entire Abyss from the fourth layer, and reaches Nat and Shiggy. The montage ends with Nanachi taking one last look at their home before they leave with Riko and Reg to move further into the Abyss.
Nanachi being willing to return as Bondrewd's "assistant" if Reg and Riko remained unharmed and can continue their dive. Considering all the awful memories being in Idofront must give them, it's quite sweet even though Bondrewd has already ruined that deal.
When Nanachi manages to return Reg to his senses after he became extremely violent when overcharged with Idolfront's electricity, they seem really happy that their voice got to him. It is a bit ruined when Reg, sporting a Raging Stiffie, confesses that it was their flufiness, earning a Dope Slap from Nanachi, but still, it's nice to see that Nanachi feels happy to have a connection with Reg.
After Faputa fulfills her duty and lays Vuerueko to rest she has no real idea what to do next and is clearly hurting. Without hesitation, Reg asks her to join the group since, as he puts it, even though he doesn't have his full memories of her, he saw everything that the present Faputa is and wants to go on adventures with her. Faputa says she'll think about it and seemingly heads off at the end of the chapter, but by the next she is revealed to have been following them and pretty much becomes a new companion for our heroes. She's a much happier Hollow for it too.
Riko herself admits to Prushka in a dream conversation with her that she was going to ask Faputa herself if Reg didn't, happy that he took initiative in that regard. Bear in mind, Faputa was going to try and kill her for "stealing Reg away," and yet Riko doesn't seem to hold a grudge. In fact, the two of them seem to bond pretty quickly.
Upon reaching a part of the sixth layer where the team sees an Emperors Shell Turtle for the first time, everyone, save Faputa, recognizes it from the story that Nanachi used to read to Mitty. Faputa does recall Mitty from the memories she inherited and regards her as cute despite being sad that she disappeared. She also states to Nanachi that she believes that the powers she gained from her will pay off in the end for Nanachi, which is enough to earn a small appreciative smile from Nanachi. Riko decides to name the area, "The Cliff of Emperor Mitty."
