Gai Amatsu

Gai Amatsu is the CEO of Zaia Enterprise Japan and the main antagonist of Kamen Rider Zero-One.

History
Gai first appeared when Yua Yaiba approached him in his office and informed him that she had discovered Hiden Intelligence's secret, that all HumaGears had an auto-data transfer device in them. She also told Gai about how she had discovered that the Progrise Keys thought to have been destroyed in the Daybreak Incident were actually still active, causing Gai to remark that "in other words", the Ark will rise again.

Gai later met with Yua again and instructed her to take down MetsubouJinrai.NET, providing her the Lightning Hornet Key, which he noted had twice the power of Rushing Cheetah, to assist her in the task.

After Yua handed the Mammoth Progrise Key over to Aruto Hiden to assist him in combating the rogue Giger, Gai met with her again and remarked that he did not expect her to hand the key over to Hiden Intelligence. Yua apologized to Gai, but Gai stated that there was no problem and that he would much rather she bring him a new Progrise Key instead as he arranged the Progrise Keys on his table.

After the movie produced by Hiden Intelligence starring a HumaGear actor faced difficulties in production due to attacks from MetsubouJinrai.NET, Yua went to inform Gai of the difficulties in production. However, Gai proclaimed that this "interesting drama of Hiden Intelligence's destruction" was still on track.

Gai later had Yua bring Aruto Hiden, CEO of Hiden Intelligence, to his office so he could meet with him to discuss the sale of Hiden Intelligence to Zaia. Welcoming him to his office, Gai summoned two red couches for them to sit on as he brought Aruto some tea and stated that he would like for him to sell Hiden Intelligence to Zaia. Aruto asked him what he meant by that, but Gai cryptically told him that it was best that he make his decision soon for the sake of his company's future.

After Aruto became Zero-One Shining Hopper and defeated the Dodo Magia Custom 2, Gai observed the battle from a distance, noting that Zero-One was now at 500% past his base power and that he looked forward to his battle with Thouser.

Yua later met with Gai again to ask whether they should keep Fuwa on duty due to his injuries, noting that he could get himself killed. However, Gai stated that they could only watch him and went on to proclaim that the Ark would guide them to a new mythology. As Yua pondered further to what Gai meant by "mythology" Gai stated it was the mythology of the Kamen Riders.