The King 2Hearts

The King 2 Hearts is set in a parallel universe where modern day South Korea is governed by a constitutional monarchy descended from the Joseon Dynasty. Lee Jae Ha is a handsome yet materialistic crown prince who doesn't care about politics and bares total reluctance for being the second successor to the throne. Lee Jae Kang, the current king, tricked him into joining a joint military collaboration with North Korea as a means to help "make him grow up".

Meanwhile, Kim Hang Ah is a North Korean Special Forces Officer who is also the daughter of a North Korean military high command official. Both Jae Ha and Hang Ah meet at the joint military training, a crucial part in establishing friendly relations between the two separate countries. Although the two met each other with a fiery disposition, Jae Ha unwittingly sparks a friendship with Hang Ah and soon, he subsequently falls in love with her. Soon, an arranged marriage is set up between the two and they eventually become engaged. While they attempt to set their differences aside and kindle a growing relationship, things suddenly take a turn for the worse when King Jae Kang and his wife were coldly assassinated by the devious Club M, who are led by John Mayer/Kim Bong Gu, a mysterious magician who wishes to remove the Royal Family and rule in their stead. Now crowned the new King of South Korea, Jae Ha must take the reigns and protect the country before it is too late. 

Cast : 

Lee Seung Gi as Lee Jae Ha / King Lee Jae Ha
Ha Ji Won as Captain Kim Hang Ah (later Queen Hang Ah)
Jo Jung Suk  as Eun Shi Kyung
Yoon Je Moon as Kim Bong Goo (a.k.a. John Mayers)
Lee Yoon Ji as Lee Jae Shin(Princess Jae-Shin)
Lee Sung Min as Lee Jae Kang (King Jae-Kang)
Lee Yeon Kyung as Park Hyun-Joo (Queen Hyun-Joo)