N-Daguba-Zeba, also referred to as Unidentified Lifeform Number Zero and known as the One Who Brings Ultimate Darkness, is the supreme ruler of the Gurongi tribe and the primary antagonist of the series. He is a stag beetle-like being who existed in ancient times as the leader of the Gurongi when they terrorized the Linto tribe. He was eventually sealed away alongside the original Kuuga after their conflict. In the present day, his burial site is disturbed by excavation, which awakens him and allows him to resurrect two hundred members of his tribe to continue the Gurongi ritual known as the Gegeru, a murderous game targeting humanity.

Daguba-Zeba is a cold and ruthless entity who considers human life completely meaningless. His sole motivation is the fulfillment of the Gegeru and the arrival of total darkness upon the world. He possesses no discernible empathy or hesitation, and he views his power as an absolute right to bring destruction. His role in the story is that of the final and most dangerous enemy, whose presence forces the protagonist Yusuke Godai to confront the darkest potential of the Kuuga power.

In terms of abilities, Daguba-Zeba possesses supernatural powers identical to the Kuuga Ultimate Form. He can control the atoms and molecules of surrounding matter, allowing him to cause spontaneous combustion in any object or person by turning them into plasma. This ability is often referred to as supernatural ignition. He also commands elemental forces such as wind, rain, thunder, and lightning. He can fire lightning bolts, create powerful gusts, and manipulate microscopic particles. His killing intent alone is strong enough to overwhelm the enhanced senses of Kuuga Pegasus Form. He can also use morphing power without needing to touch an object, a trait that demonstrates his absolute control over his abilities. During the final battle, he and Kuuga Ultimate Form instinctively seal each other’s superpowers, leading to a brutal hand-to-hand fight where their regenerative abilities are also nullified.

Daguba-Zeba’s key relationship is with Yusuke Godai as Kuuga. The two are diametrically opposed: Godai fights to protect smiles and life, while Daguba-Zeba exists to extinguish them. Their confrontation is the climax of the series. Daguba-Zeba also holds authority over all other Gurongi, including the powerful members of the Go group. His development is minimal as he is a static, almost primal force of destruction; his only change is his eventual defeat. In the final battle, after a prolonged exchange of blows, Yusuke manages to tear the neuro-like tissue extending from the spirit stone inside Daguba-Zeba’s belt, causing his death and ending the ancient threat.