Many other reviewers have written fantastic in-depth reviews so I'll keep this short. I wish this show would make up their mind. It comprises action, mystery, supernatural, and crime. What exactly does it want to be? There is so much flitting back and forth between two timelines that it's confusing.

This could have been a great action show that highlights and gives insight into the important work of mountain rangers - episodes around finding missing people, stopping mountain-related crime (eg trespassing, illegal logging, etc), and saving people in danger. That is, make the series semi-educational in the vein of what Forecasting Love & Weather did for the Korean Meteological Administration or what Where Stars Land did for airport operations. (I do have a beef with Where Stars Land and the ridiculous turn it took but that's another story). But it had to attempt to be different. There is no need to because the subject matter itself, Jirisan and its dedicated rangers, is already unique and different to so many other dramas, so focusing on that is enough.