Masked Rider Φ's (2003)

The Smart Brain corporation, the world's most powerful corporation, is trying to take over the world using Orphnoch, the "next stage in humanity's evolution", to covertly kill off the human population. In pursuit of this, they develop three suits of power armor, called Rider Gears (each for Faiz, Kaixa, and Delta), to find and protect the Orphnoch King, who can fix a defect within Orphnoch DNA which causes their genetic structure to break down, leading to death."