Mizky Segawa was the daughter of Dr. Tetsu Segawa. She worked at Miss Jensen's Aikido school and was the girlfriend of Aikido student Sean Barker. She knew nothing of her father's work with the Chronos Corporation, and so when Max Reed arrived at the Aikido school with the news that her father had been killed while trying to deliver a dangerous weapon into his hands, she was extremely surprised. Unfortunately for her, the men who'd killed her father soon thought that Dr. Segawa had given the Guyver to her, and she was actively sought by them.
Sean and Max protected her for as long as they could, but were no match for the kidnappers when they turned into Zoanoids, even when Sean used the Guyver. Sean was killed, and then Lisker, Striker and Ramsey took Mizky, Max and the Guyver back to Chronos. Mizky was held captive by the Zoalord himself, Fulton Balcus. He demanded to know how Sean had activated the Guyver unit, threatening to turn her into a Zoanoid, too. She instead kicked Balcus in the groin and stole the Guyver. It then rebuilt Sean's body after it was swallowed by Dr. East during her struggle for possession of it with Striker, allowing him to come to Mizky's rescue and defeat the evil Zoanoids. The pair then left the Chronos labs together.