He was portrayed by Masahiro Kobayashi.
34 years prior to the start of Kabuto, Negishi and the other Natives landed on Earth in a meteorite that struck it in 1971. The Natives warned of a second wave of Worms that were coming to invade Earth and founded ZECT with Riku Kagami to develop the Masked Rider System and the Zecters in order to deal with them. However, secretly, the Natives also harbored other desires.
Negishi at first appears as an ally to the Kamen Riders, introducing himself as a "fan" of Kabuto. However, it is eventually revealed that he and the Natives are conspiring with ZECT to turn all of humanity into Natives, believing that peaceful coexistence between the two races would be impossible. When Riku deviates from the plan, Negishi and Masato Mishima deposes him as leader of ZECT so that Mishima can take his place.
Negishi later meets his demise when Dark Kabuto sacrifices himself to drag Negishi inside a TV studio that explodes and kills both of them.