On top of its strong performance on the chart, it also garnered high viewership ratings. The final episode broadcast Tuesday recorded a 14.4 percent rating, the fourth-highest rating ever for a drama on the cable channel. 

It smashed other competitors aired in the same time slot, including "Matrimonial Chaos" on KBS 2TV with 3.1 percent and "Where Stars Land" on SBS TV with 8.6 percent.

The series, set in the Joseon era (1392-1910), features an interesting love story between an unlikely couple: The prince, played by D.O., loses his memory following an accident and gets to marry the country's oldest single woman, who doesn't know her husband's true identity and thinks him useless and completely out of touch with reality.

Critics say the drama's solid plot, a clever mix of romance and political tension, as well as the two main character's great chemistry, are attributed to its success. Through the show, Do Kyung-soo, also known as D.O. from popular boy band EXO, who played two different characters of E-yul, the prince, and his amnesiac alter-ego Won-deuk, has successfully established himself as an actor.

The CPI, created by CJ ENM and Nielsen Korea, measures the level of popularity, social media presence and influence on consumer behavior of entertainment TV programs aired on the three major terrestrial networks -- MBC, SBS and KBS -- and the seven cable channels owned by CJ ENM -- including tvN, Mnet and OCN -- during prime time. JTBC, another cable network that airs some highly popular entertainment shows and dramas, is not included in the measurement. (Yonhap)