Lee Young-jin – Actress Lee Yo-won

36 years old. A spy with the code name “Bluebird”.
After losing her parents during the Donghak Peasant Revolution and becoming the sole survivor of a ruined village, she adopted by Hiroshi who was Japanese army doctor and raised without lacking anything. She started studying medicine at her father’s suggestion. With her surprising concentration, she becomes the first female surgeon of Joseon and works at Jahye Hospital after returning to her motherland. One day, she involuntarily becomes involved in an explosion at the hospital. She ends up going to Shanghai to study at the School of Medicine at Jiao Tong University, the school all skilled medical students and professors of the time graduated from, before returning and working as a doctor at the Government General of Joseon.
After a fateful meeting with Kim Won-bong, she had a time of struggle but after all, she stood on Kim Won-bong’s side. Her code name is Bluebird and she is an unidentified spy that known to take a deep breath to switch faces.

Kim Won-bong – Starring Yoo Ji-tae

39 years old. Head of the Heroic Corps.
He was a weirdo in middle school that collected all the Japanese flags that handed to celebrate the Japanese emperor’s birthday and stuck them in a toilet. He was born a rebel, but his rebellious tendency amplified and exploded when the people of Joseon are discriminated under the rule of the Japanese occupation and after experiencing military rule.
He enters University of Nanking at age 20 and seeks asylum there. After hearing about the March 1st Movement, he quits his studies and heads to West Jiandao. There, he learns how to manufacture bombs and prepares to fight against Japan. He forms the Heroic Corps with friends that graduated from a newly rising military school for an armed resistance against the Japanese colonial rule.
Won-bong believes that violence and destruction is the only way to make Japan give up its rule over Joseon. The fiery heart, the fiery force of action, is absent.
There is conflict between him and Young Jin regarding the armed opposition, but he persuades Young Jin and succeeds in forming the Korean Patriotic Legion.

Fukuda – Lim Ju-hwan

32 years old. Prosecutor of the Government General of Joseon Legal Affairs Bureau.
His father is a politician that holds various posts as the Minister for Foreign Affairs in Japan’s Cabinet. He was always elite that did not go against his parents’ wishes. He received Western education while he was young, and he is a well-mannered man. Because of this, he is always the most popular to women at the Government General, court, and at his fraternity. However, he never met anyone he could truly love. He is against discriminating the people of Joseon and goes to work at the Government General after turning down a job offer that would put him on the fast track to success to help Joseon reform and open its doors and ports to foreign trade.
He is in charge of dissidents and always tries to be fair. His life changes after meeting Young-jin in the interrogation room of Jongno Police station. Even though Young-jin is Korean and older than him, he falls in love and approaches to her to gain her heart. For Young-jin, Fukuda makes a stable future as a woman compare to Won-bong. After recognition of the identity of dual spy Young-jin, he turns into betrayal and self-defeating. He begins to tighten the breath of Young-jin and Won-bong as a prosecutor of the government general of Joseong Legal affairs bereau.

Miki – Nam Gyu-ri

29 years old. A jazz singer at Gyeongseong Club.
Not only have the men who come to Gyeongseong Club but also those people in Jongno to see her sexiness and bold charm loved her. There is a rumor that she is the only daughter of a fallen politician, but it not identified. Many pro-Japanese came forward to become her guardian, but no one was able to win Miki’s heart. She lived in America and Shanghai, and she understands well on the Western culture. She is not on by old-fashioned ideas of relationships between men and women. She chooses the men she chooses to be with and does not intend to rely on a man to take care of her. Straightforward and bold, she sometimes surprises the people around her. She looked down and Young-jin when she first met her, but that was just a defense mechanism. She later sees Young-jin’s sincerity and they become best friends. When Fukuda, whom she had a crush on, seems to have feelings for Young-jin, she becomes conflicted. With the strong sixth sense she was born with, she notices Young-jin’s double life before anyone else does.