Within the grounds of the Hagi Castle ruins there are not many buildings. A small storehouse, a fairly modern shrine, but there is also a small traditional teahouse set among some gardens.
Of all the times I have been there it has only been open once, but there always seems to be someone working on the gardens.
I believe it is possible to have tea here but I can find no information as to when or how much.
It is a nice place to wander and take pics though....