This small stone building over the pond in the northern half of the Ritsurin Garden used to be a place to watch ducks during the Edo Period, and probably hunt them too. And actually that makes me wonder. If Japanese people used to eat ducks a few Centuries
Those two houses are traditional houses from the Edo Period that can be seen at Shikoku Mura in Takamatsu. A place I warmly advise you to visit if you’re ever in Takamatsu.