I-lin: Starring Jung Il-woo

He was supposed to be the first in line to succeed the throne but King Hae-jong banished him in a fit of rage and jealousy when he was just a young boy. He is tall and stands up for justice. He is popular with the ladies. He harbors a secret ability to see ghosts and pretends to not see them when they are floating around him. But by chance he meets Do-ha who can sense the existence of ghosts and also talk to them and so together, they join forces to hunt down evil demons as royal watchmen…

Mu-seok: Starring Jung Yoon-ho

He was born in a family of warriors and trained to become the strongest swordsman in all of Joseon. He is a high-ranking officer and has good looks. His is as confident as the reckless I-lin but unlike him, he is a stickler to rules.
He has a sad memory of his mother who died when he was still a young boy but after meeting Do-ha, he starts to fall in love with her.

Do-ha: Starring Koh Sung-hee

She is from the Mago tribe and grew up in the forest where she ran with wild animals to become a strong woman. She is illiterate but she has a deep connection with nature. She goes to Hanyang, the capita, to search for her sister who was kidnapped and encounters I-lin. Together with I-lin and Mu-seok, she becomes a royal watchman. With no family or friends in the city, she finds herself drawn to I-lin who befriends her and they fall in love.

Soo-ryeon: Starring Seo Ye-ji

She is the daughter of Park Soo-jong, a powerful man in the royal court. Although she appears to be a sweet young lady, she is full of pride. Aware that her father's position gives her special privileges, she has ambitions to seek greater power. But when it comes to romance, she finds herself acting like a timid woman. Though she likes I-lin, he constantly rebuffs her advances, which breaks her heart.