Güliedistodiez, also known by the nicknames Kuro, Black, or Gyurie, is a major character in the series. He is an ancient dragon god who serves as one of the administrators of the System that governs his world. His physical appearance is striking; his skin is extremely dark, completely devoid of color, and his hair is black, which makes his eerily red eyes the only source of color on his person.

His origins trace back thousands of years, beginning when he was a young dragon god who held a deep disdain for humanity. This perspective was fundamentally changed by his encounter with Sariel, an angel dedicated to protecting humanity. Witnessing her selfless devotion and her refusal to use her godly powers to directly aid primitive lifeforms cultivated a profound respect for humans within him. When the planet faced energy depletion and Sariel prepared to sacrifice herself to replenish it, Güliedistodiez intervened by seeking the aid of a higher-ranking god named D. This act directly led to the creation of the System, a planetary mechanism designed to gather energy from mortal skills and magic to slowly heal the world. Sariel ultimately became trapped as the core of this System, and Güliedistodiez swore that he would protect humanity in her place and one day return to rescue her.

Personality-wise, Güliedistodiez is a quiet and thoughtful individual who usually places the safety of others before his own. His moral compass is strong, and he does not hesitate to intervene to protect the mortals of his world based on what he believes is right. However, he is often passive and indecisive, struggling to take decisive action unless a situation presents an immediate danger. He values truly understanding others, believing that shared experiences like drinking alcohol are the best way to get to know someone. Despite possessing intellectual superiority gained over millennia, he can be naive about human customs and common sense, a weakness that has been exploited by others in the past. He also harbors resentment toward the higher-ranking administrator D for her habitual meddling in world affairs.

Within the story's narrative, Güliedistodiez first encounters the protagonist after she defeats a fire dragon. He teleports to investigate the death of one of the dragons under his care, but he cannot speak her language. After D provides a smartphone to facilitate communication, he questions the protagonist briefly before leaving. Later, he returns to invite her to drink with him to better understand her. As a System administrator, his duties include overseeing dragonkind and maintaining the System under D's directives, though he frequently bends these rules to aid his allies.

His key relationships are central to his character. His unwavering loyalty is to Sariel, the goddess he swore to protect, and he carries the weight of her sacrifice in his duty to watch over the world for her sake. He shares a long history with Ariel, the Demon Lord, having known her for centuries. This connection leads him to intervene in her battles and, after the protagonist joins Ariel, to become the commander of the Ninth Demon Army under her partly to monitor the new, troublesome god. He also has a tense relationship with the protagonist, Shiraori, whom he views as a dangerous variable and potential future enemy he may be forced to eliminate. He also has a connection to Dustin, the Pope, and leaves his subordinates in his care after his defeat.

Güliedistodiez undergoes significant development from his past as an arrogant and prideful young dragon to the reserved and guilt-ridden administrator of the present. He carries immense guilt over his inaction and the role he played in the world's decline, recognizing that his passive approach has contributed to the planet's crisis. He is torn between his desire to uphold Sariel's legacy, his duty as an administrator, and the need to make hard choices to save the world, which puts him in direct opposition to the protagonist's plan to dismantle the System.

As a god, his abilities are immense and exist beyond the limits of the System. His physical strength allows him to effortlessly overpower entities like a berserk Wrath with a slight movement. He wields Magecraft, a paranormal phenomenon that allows gods to alter the fundamental laws of existence using soul energy. His most notable power is his unique Dragon Barrier or anti-Magecraft boundary field, which invalidates all magic and skills within its range, making him the natural enemy of gods who rely on spellcasting. He can also deploy a God Zone, a personal dimension where the laws of physics are entirely under his control, granting him an overwhelming advantage in combat. He is capable of teleportation, cloning by implanting his soul into other bodies, regeneration, and even surviving and operating in the vacuum of outer space.