In the Kisakata area of Nikaho City, Akita Prefecture, there is a unique landscape of rice fields dotted with many hills. This landscape is known as Kujūkushima, which means “99 islands.” The hills are hummocks that formed in the sector collapse of Mt. Chōkai approximately 2500 years ago (466 BC). Kisakata was once a shallow sea, so when the land and debris from the collapse settled below the mountain, some of it fell in the water, forming islands. This island-dotted Kisakata became popular for its spectacular scenery, and its beauty inspired many poets. Among the poets who visited was the famous Matsuo Bashō, a key figure in Japanese cultural history.

The modern scenery, however, is different from what these poets described in their works. The Kujūkushima Islands now sit on dry land. This is because in July 1804, a magnitude 7.0 earthquake occurred, causing the land to uplift about 2 m and the sea between the islands to dry up.

The scenery of the Kujūkushima Islands is an important natural record of the changes in the Earth’s crust, caused by volcanic eruptions and earthquakes. For this reason, it was designated on 22 January 1934 as a National Natural Monument. The local community carries out activities to preserve the scenery here. In addition, the Kujūkushima Islands are even introduced in international texts on volcanology as a representative example of terrain created by the sector collapse of a volcano.