Just doing a bit of googling for introductory information tells me that this is a series of films that are part of a larger universe of films and tv shows. The 17th film was loosely remade as Blind Fury in the U.S. in 1990. The first -Zatoichi the Blind Swordsman- came out in 1962 and the last one available from Hulu was released in 1964.
The first one is embedded below:
The Criterion announcement is here.
HT: /film, who says:
Now, thanks to a deal between Criterion and Hulu, you can watch six of the films, the first chapters in the long series, for free. This looks to be the first of a series of Hulu offerings from Criterion, and it’s a great start.