Omega is a sentient robot constructed by the Warp Monarch to serve as an anti-Gransazer weapon. He is the antagonist of episodes 38 and 39 of Chouseishin Gransazer.
Omega was built in the Omega Project and left on Earth by the Warp Monarch following their genocide of the ancient humans in case the Gransazers ever came back.
In the present day, Omega was unearthed in a Croatian temple and brought to Professor Horiguchi for him to analyze. Omega awoke after being touched by Mika and set off after her so she could help him gather data.
However, an encounter with Ran causes his anti-Gransazer programming to awaken. Omega then fights Sazer Mithras, but finds himself unable to kill her. Confused, Omega contacts the Warp Monarch, who disable his independent thinking circuit. Omega is then ordered by the Warp Monarch Council to eliminate all 12 Gransazers.
Omega contacts Mika and tells her to bring all 12 Gransazers to him. Mika later goes to meet him, where Omega reveals to Mika that the Warp Monarch disabled his independent thinking circuit. Omega then switches from his human guise to his true robot form and goes to eliminate Mika, who transforms into Sazer Mithras. The two fight and several other Gransazers show up to assist Mika in beating Omega back. Omega then transforms into a giant, more monstrous looking creature and goes on a rampage. In response to this, the Gransazers summon their Chouseishin and combine to form DaiSazer. DaiSazer eventually triumphs over Omega and defeats him.
Later, Mika and the other Gransazers find Omega in the woods. Unfortunately, the presence of all 12 Gransazers causes Omega's self-destruct system to activate. Omega quickly runs away from the Gransazers before exploding to prevent himself from hurting Mika.