Hagi Okan was constructed in 1607 after Hagi castle was built to connect Mitajiri(Bofu) and the castle foot in the shortest distance as a Sankinkotai road. 52.7km long highway of Sanin and Sanyo.

It played an important role for people in the modern period around Meiji restoration.

Originally it was made radially in all directions from Yamaguchi in Muromachi era and got organized again in Edo period.

Country border monuments, Ichinozaka milestone, and Rokkenchaya are related remains.