Reg is a robotic being who appears to be a little boy. His actual age, origins, and even name are unknown because he cannot recall anything about his life before his encounter with Riko. He is named after a dog Riko used to have. Having a seemingly artificial body, Reg might be the only being completely immune to the Curse of the Abyss. Because of this, he is sometimes referred to as "The Treasure of the Deep." Reg’s body is extremely durable, even to the point that Ozen the Immovable 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 has a very high pain tolerance. His senses of smell and hearing are strong, one comparable to a dog. His arms can extend up to 40 meters each and can shoot them to the top of cliffs or grab things very far away. The cords attached are very durable. He is also equipped with an incinerator, which is a powerful incendiary cannon built into his hands and feet, emitting a beam of light, indicating the area to eliminate, penetrating through objects. Objects within the range of the light break apart and are absorbed into the spinning axes. The incinerator is connected to the Abyss in an unknown way, having the power to rewrite the rules of the Abyss. Reg passes out for 2 hours upon use, but it can be fired multiple times in the 10-minute deadline, and can also be set to not affect living beings. 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 often said.
