Nanashi, whose name means "Nameless" in Japanese, is a half-yōkai who serves as the main antagonist of the first half of the 2018 anime adaptation of GeGeGe no Kitarō. Appearing as a tall, ominous figure perpetually surrounded by a dark aura, he wears a mask and a full black outfit that conceal his true appearance, which hints at a withered, inhuman form beneath. His background is rooted in his identity as a hanyō, a being born of both human and yōkai heritage, and his name reflects his lack of a fixed identity or place in the world. Nanashi is driven by cryptic and mysterious goals, primarily centered on absorbing the resentment and hatred of others to fuel his own power. His motivations are not rooted in personal vendettas but in a broader, almost philosophical desire to consume negative emotions and grow stronger, ultimately seeking transformation or evolution. In the story, he functions as a recurring and formidable threat, orchestrating events that challenge the main characters and force them to confront darker aspects of the yōkai and human worlds. His key relationships are primarily adversarial, especially with Kitarō and his allies, whom he views as obstacles or as sources of the conflict he seeks to exploit. He also interacts with other characters through the placement of seals based on the five elements of Wu Xing, binding their powers or altering their abilities. Over the course of the narrative, Nanashi undergoes significant development, notably achieving a powered-up state where he becomes gigantic and takes on the appearance of a young baby with four eyes, a form that allows him to absorb even greater amounts of resentment and hatred. His notable abilities include the manipulation of dark energies, the use of elemental seals that grant or restrict powers, and the capacity to consume negative emotions to increase his own strength, making him a versatile and increasingly dangerous opponent as the story progresses.