Xishi is a beautiful peasant girl from the conquered Yue kingdom who harbors a deep hatred for the occupying Wu forces following the murder of her little sister. Chosen to act as a tribute concubine and spy, she undergoes intense training to weaponize her beauty and charm the enemy king. She is compassionate and observant, struggling to balance the heavy burden of her vengeful mission with her natural empathy for others.

Fanli is the highly respected, incorruptible political and military advisor to King Goujian of the Yue. Renowned for his intelligence and combat skills, he recruits Xishi and trains her in the arts of espionage, etiquette, and emotional control. He maintains a strict dedication to his kingdom's cause, keeping his own heart at a distance even as he develops feelings for his beautiful protégé.

Zhengdan is a fierce village girl who prefers physical combat and horseback riding over traditional women's roles. Harboring a thirst for vengeance against the Wu soldier who killed her father, she eagerly joins Xishi as a fellow spy. Her bold, action-oriented nature contrasts sharply with Xishi's quieter, more subtle approach to espionage.

Fuchai is the surprisingly young and handsome king of the conquering Wu kingdom. Having defeated the Yue in the past, he rules from a position of immense privilege but suffers from a deep, isolating loneliness. He quickly becomes enchanted by Xishi, displaying a vulnerability and capacity for affection that complicates her view of him as a one-dimensional monster.

Goujian is the calculating and ambitious ruler of the defeated Yue kingdom. Driven by the humiliation he suffered at the hands of King Fuchai, he formulates a long-term plan to use beautiful women as spies to infiltrate and weaken the Wu court from the inside. He prioritizes political victory and revenge over the personal safety and feelings of his subjects.

General Ma is a formidable and brutal military leader in the Wu kingdom. He commands respect through fear and violence, having killed Zhengdan's father during the initial war. He serves as a physical representation of the Wu army's cruelty toward the conquered Yue people.

Zixu is a highly strategic advisor to King Fuchai. Originally from the state of Chu, he harbors his own motivations fueled by a desire to avenge his father's execution. He functions as a powerful, suspicious force in the Wu court, quickly doubting Xishi's true motives and working to neutralize her influence over the king.

Susu is Xishi's younger sister, whose brutal murder at the hands of a Wu soldier traumatized her family. Her memory serves as the primary emotional catalyst for Xishi's hatred of the Wu and her willingness to accept the dangerous mission to infiltrate their court.

Luyi is a loyal guard who serves Fanli and accompanies the women during their training and journey to the Wu kingdom. Taken in by Fanli after his own father died on the battlefield, he is highly observant of the growing connection between his mentor and Xishi.

Lady Yu is a concubine in King Fuchai's court whose father is a general in the guard. Fearing the loss of her position and her family's status due to Xishi's rapid rise in the king's favor, she becomes an early rival in the dangerous political games of the palace.

Xiaomin is a terrified young maid initially sent by Lady Yu to eliminate Xishi. After Xishi mercifully spares her life, Xiaomin pledges her loyalty to the Yue spy, providing valuable information about court rumors and helping her manage the complex social structure of the palace.

Bo Pi is a minister in the Wu court who is secretly operating as a spy for the Yue kingdom. He uses his position to counter Zixu and General Ma's aggressive military advice, helping to steer King Fuchai away from attacking King Goujian.