Neizu, also known as Neiz or Naise, is a member of Cooler's Armored Squadron within the Cooler Force. He is a tall, brown reptilian humanoid with large yellow eyes and pointed ears. His homeworld is Planet Cooler No. 6, formerly known as Planet Zalt, a world covered almost entirely in water, and his race evolved from an amphibious species. Among the squadron, Neizu has the lowest power level, but he compensates with unusual physical traits and a proud attitude, particularly valuing his speed.

Neizu is fiercely loyal to Cooler, stressing the importance of his master's opinions above all else. He is an elite soldier who carries out orders without hesitation, and he takes the mission to Earth seriously: to find and eliminate the Saiyan who defeated Frieza, as well as any other remaining Saiyans. His personality is marked by a certain arrogance, and he delights in displaying his abilities, such as when he knocks out Krillin with a single punch or deflects a ki blast from Goku.

In the film Dragon Ball Z: Cooler's Revenge, Neizu first appears alongside his comrades Salza and Dore, ambushing Goku and his friends during a camping trip. During the initial skirmish, he accidentally kicks Dore while trying to attack Goku, and he narrowly avoids a direct hit by retracting his head into his body—a unique defensive technique that allows his head to disappear into his shoulders like a turtle's. After Cooler injures Goku and the heroes escape, Neizu and the others begin ravaging the forest to flush them out. When Gohan returns with Senzu Beans, Neizu intercepts him, only to be confronted by Piccolo. Piccolo kills Dore with a ki blast that Neizu evades by again hiding his head, but the blast was actually aimed at Dore. After Dore's death, Neizu attempts to subdue Piccolo with a high-voltage electrical attack called the Neiz Bind Wave. Believing Piccolo is immobilized, Neizu moves in to gloat, but Piccolo grabs him and reflects the attack back, killing Neizu instantly.

Neizu's key relationships are with his master Cooler, whom he serves with absolute devotion, and his fellow squadron members Salza and Dore, with whom he works as a cohesive unit. He shows no development or growth in the film, as he is defeated shortly after his introduction. Notable abilities include his head-retraction technique, which allows him to dodge attacks, and his electrical organ, which enables him to generate and discharge powerful shocks. He is also capable of flight and energy attacks, such as the Super Energy Wave Volley performed in tandem with Dore and Salza.