When Tiz first appears in the series Jyu Oh Sei she is about 13 years old and is the second in command of the Sun Ring females. After she sees Thor battling, she immediately takes a liking to him and demands that he be her husband, though Thor refuses. She even leaves the Sun Ring (which is not allowed) just to be with Thor.
She continues to follow Thor around in his adventures until one day Chen, the leader (or "Top"), of the Sun Ring comes looking for her so she can take Tiz back to the Sun Ring stronghold. By now Thor has warmed up to Tiz and fights Chen for her freedom. After Thor becomes Top of the Ochre Ring Tiz becomes his second.
Four years later Tiz and Thor have become much closer. Tiz tells Thor on many occasions to let her have his baby. Living on a planet where most people don't live past 30 and there is only one month per year in which the people are allowed to mate means they shouldn't hold off. One day Thor meets a woman named Karim and almost immediately falls in love with her. Thor tells a devastated Tiz that he loves her more like a sister since they basically grew up together. Chen convinces Tiz that Thor still loves her and that she should still help support him in his quest.
Later, Tiz accompanies Thor to the space station where the Juno Prime Minister is awaiting them. After it's revealed that the planet will be terraformed, thus killing all who inhabit it, Thor tells Tiz to help the people get to safety while he tries to stop the computer system from starting the process. He also tells Tiz that he will be the Father of her child.
Back on the surface of Chimera, Tiz is helping everyone get to safety, even Thor's rival, Zagi. When someone tries shooting Zagi, Tiz jumps in front of the bullet. Right after there is an earthquake that sends Zagi and Tiz down into a deep crevasse. At the bottom of the hole, Tiz dies in Zagi's arms.
An unspecified amount of time later back on the planet Chimera, Thor and Chen find an abandoned child with no name. Thor names her Tiz.