This is going to be a bit vague and brief. I haven't figured out how to touch on its themes without diluting its poignancy or giving important things away. If you're considering watching it, just go ahead. It's only two hours and, in my opinion, well worth the time.

*This review is also written from the point of view of a western viewer who pays attention but still has much to learn. Some of my sense of disorientation came from the combination of a short story's brevity and it clearly being made for an audience who readily understands context I had to piece in from elsewhere, like SOTUS hazing, or wonder about. None of this was a deal breaker by any means - that sense of old but new-to-me things to learn about is lovely - and everything which needed to came clear in the end.

The beginning is uneven. A 40 year old actor plays a 1st year uni student in flashbacks. His SOTUS seniors look like they have lived. A lot. It skips around so it's not clear if it's a bit of a ghost story or what's really going on.* There's a brief touch of tourism promotion for the Dan Sai district (Loei province, NE Thailand) and a decent amount of education about one of their customs, the masks of its title.

As the series progresses though, it more clearly becomes a moving and poignant short story. I'm not telling you about what. If you want to know, watch :)

Perhaps it is also a love letter to the Dan Sai people. I hope to learn much more about them.