4, which was built in the early Kofun period (around the middle of the 4th century) and which a total length of about 100 meters, is the largest, and includes a pit-style stone burial chamber and a cylindrical haniwa-style coffin.

The interior was filled with red clay, and the exterior covered in plate-like stones and cylindrical haniwa.

Grave goods recovered include triangular-rimmed divine beast bronze mirrors, jade magatama and jasper cylindrical beads.

Tumulus No.4 is presumed to be one of the earliest keyhole-shaped kofun in the eastern portion of Hōki Province.

[2] The tumulus cluster is located 30-minutes by car from Kurayoshi Station on the JR West San'in Main Line.