The Choi and Kang clans have a deep dark secret in the past as to why they have a deep conflict with each other. Centuries ago, the Choi clan and Kang clan had a good relationship together. That is until the 3rd Choi king betrayed his best friend, the 3rd Kang king and killed the 3rd Kang king's younger brother due to a misunderstanding which resulted in a bad relationship between the two clans from that on until now.