Jung Sung-mo

During the reign of King Sejong in the 15th century, the Joseon Dynasty was the embodiment of the perfect state. To the Ming China, the aspiring imperial power, Joseon presented an obstacle to territorial expansion. To protect themselves from war, King Sejong develops a secret weapon to defend their territory and take back their land and supremacy.

Minwoo, a medical student, feels pure love for Dahye, whom he bumped into while riding his bicycle on campus. With Hyun-tae's help, they meet again and begin to understand and love each other. Around this time, Min-woo's father is hospitalized due to a stroke caused by a business failure, and her half-brother, who was recognized as her father's successor, flees to the United States and reveals the secret of Min-woo's birth. When creditors gather to harass his sick father, Min-woo tries to dissuade them, but then hits and injures an old man and runs away. Da-hye visits Min-woo's refuge and persuades him to surrender. After serving his time in prison, Min-woo hears from Hyeon-tae and Da-hye about his father's death. After that, he leaves Da-hye and sets out to find her biological aunt.