They run from west to east and include: Mount Hiruzen has been settled from the Japanese stone age.

The Yayoi period (300 BCE–250 CE) saw a great population increase to the area south of Hiruzen.

In the Sengoku period (1467–1573) the Hiruzen region was contested by the Yamana, Akamatsu, Miura and other clans.

The lake supported an extensive population of diatoms for nearly 50,000 years, and Diatomaceous soil on the plain reaches 100 metres (330 ft) deep in some areas.

Lake Hiruzenbara was gradually eroded on its eastern perimeter by the Asahi River, and dried up and disappeared over time.

The Shiogama-reisen Cold Spring is designated as the source of the river, and is a protected natural habitat of the Japanese giant salamander.

[10] Yubara Dam, on the upper reaches of the Asahi, is approximately 12 kilometres (7.5 mi) from Hiruzen and was completed in 1952.