Wang Won – Starring Im Si-wan

Crown prince of Goryeo who harbors secret ambitions to conquer other lands while appearing to be kind and virtuous.
Son of the Goryeo king and grandson of the Yuan Emperor, he was anointed as the crown prince at the age of three. Because his mother was Chinese, this made him the first mixed race crown prince in the kingdom’s history. He mostly grew up alone until he met Wang Lin when he was twelve and they quickly became friends. He despises power because it causes people to hate him, so he masks his keen intelligence in order to be accepted by others. For many years, he thought little of his earthly existence and did not fear dying until he met one woman. He learned that they shared a karmic connection when they were younger and it involved a red thread. But there was a third person who had also touched the red thread.

Eun San – Starring Im Yoon-a

A young lady who destroys a bromance between two men with her beauty
She is the only daughter of a wealthy merchant named Eun Young-baek. Her mother died under mysterious circumstances so her father switched her identity with a young female servant to protect her from harm. San soon leaves home and grows up as a disciple of scholar Lee Seung-hyoo. Her mother left a will behind before her death and two boys hand-delivered it to her. These boys are forever etched into her memory. Then one day, she met them again. Because there was a karmic connection between her and the two boys, they quickly became friends. When it was time to say good-bye to her new friends, she found herself hesitating to leave. The beginnings of raging passion had sprouted during their short time together.

Wang Lin – Starring Hong Jong-hyun

More passionate about love than most, he was born into royalty and has a good character and sublime elegance of a crane.
He is the third son of grand prince Soo Sa-gong, and his family is cousins with the king of Goryeo. Because he is a virtuous and well-liked blue-blooded royal family member, people in the royal court would rather see him become the next king instead of Wang Won. But he has no interest in the throne and cherishes his friendship with Won. Then the crown prince met a girl. But she was someone that he had approached first and had been smitten in love with. He tried to suppress his feelings for her with the hopes that he would soon forget her but it was useless. Members of the royal court noticed his frayed relationship with the crown prince and started to test it so that they could convince him to join their side in mounting a coup.