Waju means an area that protects villages and farmland from flood damage.
Under the area of the Kiso-Sansen river, there is a lot of flooding disasters, so the ancestors built walls and created wajus.
"Waju-no sato" is an complexed facility where introduces local history, culture, and products.
You can experience making seaweed laver, and harvesting seasonal vegetables. You can also buy local products there.
[TripAdvisor]
https://www.tripadvisor.jp/Attraction_Review-g651657-d8600067-Reviews-Waju_no_Sato-Kuwana_Mie_Prefecture_Kinki.html