The series continue to be average. In fact, it would be below average if there wasn't such a charismatic and interesting movie star behind it! It seems like all you need to do to create a documentary nowadays is a lot of money, be a famous person and have cutting-edge tech equipment.
Make no mistake: There's no science in this documentary. This is just another form of entertainment masked with "science", "experts", "research" and the like. There aren't more than 2 experts consulted on any topic and there isn't a single serious research cited. They don't even explain how cold works in the basic level so the body reaps the benefits. The documentary is not really informative but its visuals keep you connected to the episode.
In one part of the documentary, they talk about a Shugendo ritual. It was really interesting, but they said very little about it. They showed a man doing one of the rituals but they didn't mention how long was the ritual for him, what were the health risks, how many times does he have to do that, what's the temperature of the water, etc. Even TikTok can be more informative that this!
Cool cinematography and music, though.