Goki, also known as Gouki, is a minor antagonist and the first demon formally confronted by Yusuke Urameshi in his new role as a Spirit Detective. His name, which translates to Strong Ogre, accurately reflects his nature as a brutish and powerful creature.

Goki is a demon classified as a Kyukonki, or spirit-sucking ogre. His true appearance is that of a massive, muscular red-skinned humanoid with long black hair and five horns on his head, consisting of a set of three large horns and two smaller ones. He also has long, horn-like nails on his hands and feet. To move unnoticed in the human world, he can adopt the disguise of a very large, muscular man with much shorter hair, typically dressed in a tight green shirt and blue jeans.

In terms of personality, Goki is depicted as a violent, selfish, and bloodthirsty demon who acts purely to satisfy his own desires and hunger. He is straightforward about his goal, which is to feed on human souls, and he shows no remorse for his actions, particularly targeting young children. His aggressive nature extends to his allies; he initially did not trust his partner Kurama and had to be convinced to work with him through brute force. His motivations are simple and predatory. He is driven by an insatiable appetite for human souls, and he steals the Orb of Baast, one of the Artifacts of Darkness, specifically because it serves as a perfect tool to collect and store the souls of his victims for later consumption.

Goki's role in the story is to serve as the first major test for Yusuke. After escaping from the Spirit World with the Orb of Baast, his activities of stealing children's souls bring him to Yusuke's attention. He acts as a secondary antagonist, allied with Hiei and Kurama in the theft of the three Artifacts of Darkness, but he is primarily focused on his own gruesome goal. The conflict between Yusuke and Goki forms the core of the second episode, establishing the stakes of Yusuke's new mission and the danger posed by demons from the Spirit World. His key relationships are utilitarian. He forms an alliance with Kurama and Hiei to steal the artifacts, but this partnership is one of convenience rather than loyalty. He shows no regard for his allies, and his demise is observed indifferently by Kurama, who does not intervene in the fight.

In terms of development, Goki remains a static character. He is introduced as a violent monster and is ultimately defeated and killed by Yusuke without undergoing any change or redemption. His primary narrative function is to be overcome, demonstrating the protagonist's growth. After Yusuke struggles against him in their first encounter, he learns from his mistakes and ultimately defeats Goki by firing his newly developed Spirit Gun into the demon's open mouth. Goki's defeat results in the retrieval of the Orb of Baast and the release of the children's souls he had captured.

Goki possesses several notable abilities. His most prominent trait is his monstrous physical strength, which allows him to easily overpower Yusuke in their first encounter. His demon skin is said to be as tough as steel, granting him immense durability and making him resistant to conventional attacks. He is capable of transforming between his human disguise and his full demon form, the latter of which further augments his already formidable attack and defense. Using the Orb of Baast, he can perform a technique called Soul Swallow, which allows him to absorb the souls of his victims, typically children, to increase his own strength. Despite his power, his unintelligent and cocky nature is his primary weakness, which Yusuke ultimately exploits to defeat him.