The Inaba were the feudal lords of the Usuki Domain in present-day Oita for most of the Edo Period. When the domains were abolished in the late 19th Century the famiy were made peers and moved to Tokyo
Shimo Yashiki means "lower samurai residence", bvut what it means in this case is "second home". In the first decade of the twentieth century this large residence wwas built for them to stay in whenever they visited Usuki.
Though built in modern times it is a traditional set of buildings and also has some nice gardens.
It is located not far from the castle ruins in downtown Usuki, and if you enjoy traditional japanese architecture it is worth a visit.