The beginning was unbelievable boring, it took about halfway through the drama before it started to be "decent" enough. I miss the days when thriller/mystery didn't feel the need to pad itself with side cases to keep viewers attention. I always find this structure to be flawed even when these side cases are slightly related to the main one. In the case of this drama, I would prefer if it was a constant confrontation with the main villain instead of sprinkled hints and tons of flashbacks. Speaking of villains, none of them interested me, was kinda disappointed after 16 episodes of teasing of the masked villain. Low-key kinda like an anime villain. The villain identity felt like a last minute decision instead of a calculated one. The young leads were fine but a bit bland, I would prefer more rigid actors which would suit the drama better.