Rhoma Grace is the 16-year-old protagonist. She is Cancrian.
An Acolyte studying at the Cancrian Academy on Elara, the largest moon in the Crab constellation, when her planet and its moons are destroyed in an attack only she foresaw.
Cancer's Guardian is killed, and the stars choose Rho to take her place. She must now join the other survivors from her House, without knowing whether her dad and brother are alive, and begin her Zodai training and select her council of Advisors. Rho asks Lodestar Mathias Thais, her childhood crush and the Zodai who escorted her and her friends to safety, to be her Guide.
The night of her swearing-in Ceremony, Rho comes face to face with a legendary monster, and she realizes other Houses are going to be attacked, just as Cancer was--and she's the only one who can see the threat. The only one who knows who's responsible.
She takes off with Mathias to warn the other Houses, and in their haste, they commandeer a bullet-ship whose owner is still on board. Diplomatic envoy Hysan Dax of House Libra joins their adventure and proves to be an invaluable resource--only the more time they spend with him, they more Rho and Mathias realize Hysan's smile hides much more than it reveals....
At the beginning of the book on page 20, Rho states that "Back home, I [Rho] had a sun-kissed golden tan." However, being on the moon Elara, she now has pale and pasty skin. She, like all Cancrians, has curly hair. Cancrians hair span from every hair shade but Rho's happens to be bleached from the sun exposure. Lastly, all Cancrians have "eyes, which reflect the Cancer Sea." Which means her eyes are a sea blue.