<Tr> <Th_colspan="2"> External links </Th> </Tr> <Tr> <Th> Website </Th> <Td> www.imbc.com/broad/tv/drama/gunju </Td> </Tr> <P> The Emperor: Owner of the Mask (Hangul: 군주 - 가면 의 주인; RR: Gunju--Gamyeonui juin; lit . Ruler--Master of the Mask) is a South Korean television series starring Yoo Seung - ho, Kim So - hyun, Kim Myung - soo, Yoon So - hee, Heo Joon - ho and Park Chul - min . It aired on MBC every Wednesday and Thursday at 22: 00 (KST) from May 10, 2017 for 40 episodes . </P> <P> Emperor was expected to be a hit like the popular series Love in the Moonlight (2016), but it only performed modestly with average rating of 12.4% even after extensive promotions . HanCinema also described the production as "irredeemably stupid". </P>

How many episode is ruler master of the mask