Soga no Umako
The Ishibutai Kofun was first excavated by the archaeologist and academic Kōsaku Hamada (1881－1938). Imperial kofun have not been readily excavated in Japan. Due to its association with Soga no Umako, the Ishibutai tumulus does not have an imperial designation, and has thus seen extensive excavation. The kofun was first excavated in 1933, work on the base and moat began in 1935, and excavation of the tomb continued until 1975.