Black Star Dragon Ball Arc
Nezi and the rest of the Sigma Force first appear while Goku, Pan, Trunks and Giru are searching around the planet M-2. Giru leads the group to the Sigma Force upon orders from General Rilldo to capture the three half-Saiyans. Nezi is able to identify that Goku is a Saiyan the moment they meet. When Bizu captures Goku and Trunks by encasing them in metal, the Sigma Force fly off to report the success of their mission.
Nezi and the rest of the Sigma Force are fed data of Goku, Trunks, and Pan's fighting styles and techniques in order to effectively fight against them. When Goku escapes from his container, Nezi begins to battle with Goku, mocking Goku's skill throughout the match. However, when Goku eventually shows more of his power and starts to overpower the Sigma Force, Nezi and the others fuse to create the Sigma Force Cannon. However, Goku still manages to defeat the Sigma Cannon with relative ease.
However, it is soon revealed that Nezi and the other members of the Sigma Force survived their encounter with Goku, and Rilldo has them ambush Goku during his battle with the Saiyan, the Sigma Force once again seemingly gaining a hold on Goku and stopping him from moving. However Goku quickly destroys them by transforming into a Super Saiyan. In response Rilldo merges with the remains of the Sigma Force to increase his own power.
Nezi can fly and fire lasers from his eyes, as well as use the Afterimage technique, a technique where the user moves so fast, they leave an illusion of themselves behind. He can also liquefy his body, which allows him to entrap people in his body, as well as fuse into the Sigma Force Cannon with Ribet and Bizu.
- In the English dub only the Sigma Force who appeared to aid Rilldo were not the original Sigma Force, and were instead "new and improved DNA Replicants".