Mount Katamuki (傾山) (1,602 m (5,256 ft)) is at the western end of the Sobo Mountain range in Ōita Prefecture.

It is now part of the Sobo, Katamuki and Okue Biosphere Reserve.

[1][2] It is believed that the foundation of the Sobo mountain range occurred in two periods of volcanic activity.

The first, around 13 million years ago, was buried in the second period of volcanic activity ending about 10 million years ago leaving the landscape seen today.

[3] From about 3 million years ago the activity of the Aso volcano caused nearby pyroclastic flow deposition.