Cinder is a 16-year-old cyborg and the only full-service mechanic at the weekly market in New Beijing. Because society looks down on her synthetic parts, she hides her metal hand and mechanical leg under heavy work gloves and cargo pants. She acts as the sole financial provider for her ungrateful adoptive family. Her technical skills draw unexpected attention when the Crown Prince personally requests her help repairing a broken android.

The 18-year-old Crown Prince of the Eastern Commonwealth faces mounting pressure as a deadly plague sweeps through New Beijing. With his father infected, he must abruptly prepare to take on the responsibilities of the emperor. He struggles with the political threat posed by a neighboring ruler and often seeks moments of escape at the local market.

Adri is Cinder’s stepmother and legal owner. She wears face powder and bright red lipstick, projecting an image of upper-class status while relying entirely on her cyborg stepdaughter for money. She harbors deep resentment toward Cinder, blaming the teenager for bringing misfortune into her household.

Queen Levana rules Luna, the moon colony, with an iron fist. She uses an innate ability called glamour to manipulate bioelectric energy, creating an illusion of exquisite beauty and controlling the thoughts of those around her. She uses the threat of war to force the Eastern Commonwealth into a political marriage.

Dr. Erland is the leading scientist of the royal letumosis research team. An older man who wears a wool hat and an oversized white lab coat, he searches desperately for a cure to the blue fever. He evaluates drafted cyborgs for his experiments, holding significant authority over their treatment in the facility.

Iko is an android legally owned by Adri, though she functions primarily as Cinder’s loyal assistant. Thanks to a unique personality chip, Iko experiences human-like interests such as a love for fashion, royal gossip, and dreaming of attending formal balls. She provides Cinder with constant emotional support.

Peony is Cinder’s younger stepsister and only human confidante. With curly dark hair and an exuberant personality, she spends her time fantasizing about the royal family and completely ignores societal prejudices against cyborgs. She treats Cinder with genuine warmth before falling suddenly ill with the plague.

Torin serves as the royal advisor to the Eastern Commonwealth. Impassive and highly logical, he guides the young prince through the immediate political crises following the outbreak of the plague in the royal family.

Sybil is the head thaumaturge to the Lunar Crown. She wears a long white coat embroidered with runes and acts as Queen Levana's primary agent on Earth, using her own mind-altering abilities to enforce her ruler's will.

Pearl is Cinder’s 17-year-old stepsister. Mirroring her mother's prejudices, she views cyborgs as subhuman and frequently directs insults at Cinder, enjoying the power imbalance in their household.

The ruler of the Eastern Commonwealth. He contracts letumosis, forcing his son to confront the terrifying prospect of ascending to the throne prematurely.

Adri's late husband. During a trip to Europe five years prior, he adopted an orphaned cyborg and brought her to New Beijing before ultimately dying of the plague.

A baker in the market square who openly despises cyborgs. Her sudden illness triggers an emergency quarantine protocol that results in her booth being burned to the ground.

The young son of the market baker. His mother explicitly warns him to stay away from the mechanic's booth.

An older-model android belonging to the royal family. She contains highly classified research data that mysteriously causes her to malfunction.

A research assistant working in the royal laboratory. She monitors blood samples and evaluates the monetary worth of cyborg parts.

A medical research assistant who helps process conscripted cyborgs at the palace laboratory.