Tōzan Han (東山藩, Sekowan: Toosan han) is one of the five Han of Sekowo. The name of the Domain literally means "eastern mountain". Together with Nanzan ("southern mountain") and Hokuzan ("northern mountain") the area was known as 三山 (Sanzan, "three mountains") by the Empire of Gao-Soto, and Sanzan was at the time the southernmost Circuit (道) of the Empire.