this is a question on the mute tag and it's probably definitely a spoiler. Can anyone watching it answer it under…
The child speaks a line in the trailer for the drama so I'm assuming he can speak in later episodes, just that he chooses not to due to PTSD. I think that's said in ep. 1. That's why the mute tag. He uses cards to communicate.
It's on Youtube. I don't know why I watched this because I'm not into experimental films, but I did. Here's the link if you're interested: https://www.youtube.com/watch?v=pURVWjA-MTc
https://www.youtube.com/playlist?list=PL33rNVtXB4P73PXCInlN8zpZwWrtP31Xf
https://www.viki.com/tv/37200c-arim-inn-the-forest#!