Hagi Castle, also known as Shizuki Castle, is a castle located in Hagi, Yamaguchi Prefecture, Japan. Mori Terumoto lost his holdings around Hiroshima and was moved to Hagi following the Battle of Sekigahara when he supported the losing side. He built Hagi Castle in 1604, and his family continued to rule over it until the Meiji Restoration. The castle was unusual as it was constructed mainly at the base of Mount Shizuki, though a few defences are located on the mountain. In 1874, much of the castle was destroyed, leaving little but ruins. The castle is a National Historic site.