Glass Mask Promotional poster for "Glass Mask" Genre Drama melodrama Revenge Written by Choi Young-in Kim Suk-gon Directed by Sun Do-joon Kim Yong-min Shin Seung-woo Starring Seo Woo Lee Ji-hoon Park Jin-woo Kim Yoon-seo Country of origin South Korea Original language(s) Korean No. of episodes 122 Production Producer(s) Lee Hyung-sun Production location(s) South Korea Running time 45 minutes Production company(s) MBC C&I Distributor tvN Release Original network tvN Picture format 1080i (HDTV) Audio format Dolby Digital First shown in South Korea Original release September 3, 2012 (2012-09-03) – April 4, 2013 (2013-04-04) External links Website