So I had to go watch the show again to figure this out for someone else. my best guess is that it looks like two separate cuts of the same cloth.
It’s hard to describe but one cut is cloth with a hole in it like a traditional poncho. The other cut is tucked into the neck hole and moves low across the chest and back around under the other piece of cloth. They are pleated in the front at the neck to join the two.
In the back the right piece over laps the left piece and looks to be sewn at the top. I think this is where the piece that tucks in the front also wraps around and is sewn.
So essentially one piece is a piece of cloth with a poncho like neck hole, and the other piece is sewn onto the back of it then tucked into the front, wrapped all the way back around and sewn again.
That’s my best guess at to how its put together based on a few stills from the first episode.
Yellow is where I believe it to be pleated and attached.
The little sketch is the view from the back. In the first episode you can see it after he gets off work and he’s walking through town. There’s a visible overlap where it’s clearly attached at the collar.
I’ve yet to try to make one myself but I provided that image and description to someone else and they got pretty decent one built based on the sketch.
I’m probably way off to how it’s really put together but I hope it helps a little.