Reg

Reg is a robot who appears to be a little boy. His actual age, origins and even name are unknown since he can't recall anything about his life before his encounter with Riko. He was named Reg by Riko after a dog she used to have.

Having an artificial body, Reg might be the only being completely immune to the Curse of the Abyss, because of that he is sometimes referred to as "The Treasure of the Deep."

According to ???, Reg could be an "Interference Unit" of one of the lower layers.

Appearance
Reg has tan skin and dark hair. He wears a metal helmet with two asymmetrical horns protruding out of the sides and what appears to be a glass lens in the front, which occasionally will glow with a strange symbol shared by all artifacts. Underneath his helmet is what looks similar to a jagged metal headband of some sort, with bolts on either side keeping it in place on his head. His ears are slightly pointed. Reg's eyes are yellow and his pupils are vertical slits, like a cat. There are two red patches of skin on his cheeks, and four more on either side of his ribcage. His eyebrows are small and gray. Though he is a robot, the only parts of him that appear to be mechanical are his arms and legs, which are bulky compared to the rest of him. He has nipples, a bellybutton, and even human genitals.

He is usually shirtless, save for the tattered red cape he was wearing when Riko found him. His pants are a washed out green and purple, are baggy, and stop just below his knees.

He later loses an arm and gets a scar in his belly button after his fight with Bondrewd. undefined

Personality
Despite being a formidable fighter, Reg is rather shy, naive, and unassertive. He blushes easily and often cries when in distress. However, when forced into danger or an unpleasant situation, he is shown to be hot-tempered and sharp, compared to Riko's analytic, noncombatant role. Regardless of his skittishness, Reg has made it his sworn duty to protect Riko, and doesn't hesitate to put up a fight when she is in harm's way.

According to Ozen, the way he speaks and handles his body is similar to Lyza. One of his favorite words to say is "irredeemable," which was a word that Lyza said often.

History
Very little is known of Reg's past, as he has none of his memories from prior to meeting Riko. He was found by Riko in the Abode of Fossils at a depth of 100-220 meters after Reg uses his incinerator to save Riko.

He presumes he is from the bottom of the abyss, as a sketch from Lyza shows a likeness to him. According to her notes, she first encountered him around the 7th layer. He had at one point before met Ozen the Unmovable, as well as supposedly been close to Faputa, though he doesn't remember any of this. As he descends further into the abyss, Reg's memories are coming back in little bits at a time. He eventually recalls that at some point he had journeyed alongside Riko's mother, though he does not remember any specific details. According to Faputa, Reg's name was Reg even before he lost his memory.

Orth Arc
While exploring and delving at the first layer, Riko is being chased by a scarlet maw, when a beam of energy hits it and chases it away. Wondering who saved her, Riko follows the wreckage from the beam to its source, where she finds an unconscious Reg. Upon further inspection, Riko realizes he is not human, and with the help of Nat, she brings Reg back to Belchero Orphanage. There she studies and takes notes on Reg's body and is able to wake him up using a jolt of electricity. She gives Reg a name, helps him settle in at the orphanage, and tells him about Orth and the Abyss.undefined

During the Resurrection Festival, a celebration of returning delvers[debatable], Habolg returns from the Abyss with the white whistle that belonged to Riko's mother, Lyza, along with some of Lyza's notes from her delving experiences. While Riko and Reg look through them, they notice one of them contains a sketch of a figure that looks like a silhouette similar to Reg, along with a note reading "I'll be waiting at the bottom of the Abyss."undefined After discussing it with Nat and Shiggy, Riko and Reg decide to leave Orth and go to the bottom of the Abyss on their own. The two take a few days to prepare and then leave the orphanage in the middle of the night. When they reach the Wharf district, a part of Orth that dips into the Abyss, Riko and Reg say their final goodbyes to Nat and Shiggy, and begin their descent towards the bottom.undefined

Descent to the Abyss Arc
After the sad goodbyes from Riko and Reg to Nat and Shiggy, they finally descend and land somewhere in the first layer of the Abyss, with a depth of 820 meters.undefined While they are eating their breakfast, Riko notices Jiruo stuck a red slip with the contents of Lyza's sealed letter and the message, "I'll depart at dawn to capture you", into their belongings: Riko rushes and packs their things with Reg's help, and they leave the premises post-haste.undefined Immediately afterwards, they land in a silkfang's territory and are ambushed by it; however, they escape while defending themselves.undefined They witness the 2nd layer for the first time. Reg suddenly hears his own voice—something about his past–and later, he accompanies Riko for a short break. While they are having a conversation, Reg sees a delver above some boulders who chases them while they rush to escape and hide—Reg defends Riko. Not very much later, the delver catches up—and is revealed to be the Black Whistle delver Habolg, who was impressed by the group's fast pace. Habolg's main objective was to meet and inspect Reg, because Nat and Shiggy told him about Reg's true nature. Instead of taking them back to Orth, he offers to escort them to the Seeker Camp, which Riko declines. He then gives Riko a warning about Ozen, some medicine, and other supplies and lets them go.undefined

Shortly after they arrive on the second layer, Riko and Reg hear a cry for help, but it's one of a corpse weeper, which mimics its victims' cries of pain and fear: they follow it. While observing the corpse weeper, they are ambushed by a colony of them, and one of them snatches Riko. She struggles initially, but she loses consciousness due to the strain of ascension. Reg, unsure of what to do, recalls his memory of using the Incinerator to save Riko from the scarlet maw in the first layer. Instinctively, he raises his arm and fires his Incinerator, obliterating the colony of corpse weepers and saving Riko from being fed to the corpse weeper's young.undefined

Seeker Camp arc
After a short climb down the top of the second layer, Reg and Riko find themselves in the company of the Immovable Lord, Ozen, at the Seeker Camp; her domain is to supervise descent past the second layer. While in the presence of Ozen; Riko and Reg make friends with Marulk, Ozen's pupil and servant. Here, Riko learns about her birth into the Abyss and her early childhood.undefined

Poison and Soul Liberation Arc
During Riko's and Reg's descent to the 4th layer they are attacked by an Orb Piercer. Druing the battle Riko's hand gets stabbed by one of the Orb Piercer's venomous needles, causing her to hallucinate and, in combination with the curse due to ascending to fast in retreat, start bleeding out of every hole in her body. Shortly afterward she looses conscious leaving Reg in despair. Nanachi reveals themself to Reg, due to seeing him crying over Riko's body. Because the two's relationship remind Nanachi of their relationship with Mitty, Nanachi decides to aid them. With Nanachi's help Reg starts to gather the ingredients needed to cure Riko. During the gathering he encounters the Orb Piercer again and, thanks to the help of Nanachi viva a communicator, is able to obliterate it with a beam from his incinerator. Nanachi, surprised by the power of it and similarity to Bondrewd's Sparagmos, asks Reg to kill Mitty with it to end her suffering. Reg, conflicted with it, follows Nanachi's wish and comforts her afterward as she breaks down in tears due to setting Mitty free but also loosing her. After Riko recovered, Nanachi decides to join Riko and Reg on their journey to the bottom of the Abyss.

Idofont Arc
After preparations, the group embarks from Nanachi's hideout, reaching the field of Eternal Fortunes. There they encounter one of Bondrewd's Praying Hands. A brief exchange follows, in which the Praying Hand tells them that Bondrewd is expecting them. Then the three of them reach Bondrewd's base, Idofront. A girl, Prushka, approaches them and asks if they are her father's guests. A few moments later Bondrewd arrives, greets the trio and informs them that entrance into the 6th layer is only possible with a personalized White Whistle. He invites them to stay a night and Prushka gives them a tour of the base. Druing the night, Reg is taken away by the Praying Hands and they start running tests on him. They even cut off his arm to further analyse it. Nanachi, Riko and Pruhska find him due to hearing his screams in the hall. Prushka orders the Praying Hands to stop treating her father's guests that way, only to be informed by them that this area is off limits for her. The Trio, together with Prushka, escapes outside the Idofront and tries to escape in a boat. Only Prushka stays back, because she wants to convince Bondrewd to return Reg's arm. Shortly afterwards Reg, Nanachi and Riko are confronted by Bondrewd and his Praying Hands again, however they have been let into a trap by the trio and are attacked by a Desert Hydra. Only Bondrewd survives the attack with his Sparagmos, but is dispatched by a clever strategy of Nanachi and Reg resulting in him being exposed to the curse aswell crushed by Reg with a boulder. Moments later Prushka and Gueira arrive and Prushka bursts out in tears over the state Bondrewd is in. Gueira quickly removes Bondrewd's mask and replaces it with his own, leading him to turn into Bondrewd in the process. Bondrewd makes the relieved Prushka pass out and and reveals to the trio that all Praying Hands are copies of him he can transfer his consciousness into. After a quick beatdown he leaves them and invites them back to the Idofront whenever they are ready. Riko notes that Bondrewd maybe uses the artifact, Zoaholic, to transfer parts of his consciousness. Together with Reg the both make a strategy in order to destroy it. As they sneak back into Idofront Nanachi and Riko make theier way into what Nanachi calls the processing room, while Reg searches for the power plant to destroy it. During that he is seemingly overloaded and wents out of control. He makes his way back into Idofron and interrupts the conversation between Bondrewd, Nanachi and Riko by attacking Bondrewd. A fight between Reg and Bondrewd breaks out. The out of control Reg blasts his incinerator without consideration for the surroundings, but Bondrewd is able to keep up with him. Only due to Nanachi's interruption, due to not wanting to see Reg in such a state and begging him to stop with a hug, the fight comes to a momentarily halt; with Reg turning back to his usual self. During the second stage of the fight Bondrewd reveals that he turned Prushka into a cartridge. This revelation causes Riko to be shaken up to tears because Prushka was a good friend to her and enrages Reg. After Bondrewd's defeat, resulting him to be cut in half, Riko holds Prushka's cartridge close to her and cries. In that moment a stone, like one needed to craft a personal White Whistle, comes out of the cartridge. Nanachi tells Riko that Prushka most likely asumed the form of the stone to be able to travel along with Riko, which relieves Riko abit. Nanachi makes a harness so Riko can wear Prushka's stone around her neck. As the group gets ready to traverse into the 6th layer, it is shown that Bondrewd's consciousness still lives on within his Praying Hands as they come to see Riko's group off.

Incinerator
The incinerator is Reg's version of Sparagmos, the Origin-Guiding Light. Any object in its path disappears, "as if it comes undone... Shortly afterwards, the surrounding air ignites to nothing." The incinerator is also capable of "tensing up" the force field of the Abyss in an undefined manner. The size of the beam changes depending on Reg's will. It is important to note that the Incinerator does not just burn objects, it is connected to the Abyss in an unknown way. The name implies that everything hit by the light returns to the Abyss; for instance when Reg kills Mitty he makes a comment about Mitty's soul "cycling again." Nanachi also comments that Reg's incinerator "has the power to rewrite the rules of the Abyss".

The incinerator is a relic that is part of Reg. All relics in the Abyss contain a pattern that signify the number of uses left before becoming useless. Along with passing out for 2 hours after 10 minutes of using the Incinerator, the pattern in Reg's helmet decreases,. Electricity seems to recharge it, as the symbol grew again after Reg was exposed to electricity at Idofront.

It could also be possible that when over used and he runs out of energy he loses his memory. This is possible why Riko was able to wake him up with a jolt of electricity.

Extendable Arms
Reg's arms can extend up to 40 meters each. He can shoot them to the top of cliffs or grab things very far away. The cord attaching them is very durable. Using these arms does not reduce the pattern on Reg's helmet because they require a minimal amount of energy.

Heightened Senses
Reg's senses of smell and hearing are stronger than that of a human's. Nanachi has commented to themself that he reminds them of a dog by the way he follows his nose. He feels simulated pain.

Super Durability
As commented on by several characters, Reg's body is extremely durable, even to the point that Ozen the Unmovable couldn't break him even when slamming him into the floor with all her strength. Despite his high durability, Reg is agile and weighs little. His wounds heal at a faster rate than a human's, and he has a very high pain tolerance. His navel is the thinnest part of his skin, making it a weak spot.

Trivia

 * Reg is often associated with dogs. He is named after a dog Riko had when she was younger, and is also sometimes compared to a dog, even by those who aren't aware of the origin of his name.
 * He is slightly disappointed that his muscles won't grow.
 * He is able to get erections, despite being a robot.
 * Akihito stated in an interview that Reg was inspired by a Cave Story character named Quote.