“Haruna Shrine in Harunasan-cho, Takasaki City, Gunma Prefecture is a historic shrine located in Mt. Haruna. The enshrined deities are Homusubi no Kami and Haniyamahime no Kami. It is one of the Six Shrines in Kozuke province (present-day Gunma Prefecture). It is said that the shrine was founded during the reign of the 2nd emperor Suizei (reigned 581-549 B.C.) and the shrine building was built in 586.” — the Nippon-Kichi
“Mt. Haruna (1,449 m) is an active volcano in Harunako-cho, Takasaki City, Gunma Prefecture. Together with Mt. Akagi and Mt. Myogi, it is one of the Three Mountains in Jomo (present-day Gunma Prefecture). The volcano has a summit caldera, which contains over fifteen peaks including the symmetrical cone of Haruna-Fuji, along with a crater lake, Lake Haruna. Although it has been inactive for a long time, it eruppted many times from the 5th to the 6th centuries. At Kuroimine Ruins in Shibukawa City at the eastern foot of the mountain, the intact remains of dwellings in the late Kofun period (A.D. 300-700) were excavated under the 2 m deposition of volcanic ashes.
The mountain itself had long been worshipped as the deity that symborizes the town, and it has Haruna Shrine and Mizusawa Kannon Temple inside the mountain area. There also remain many legends and folk tales, which include the tales of the Giant Daidarabocchi and the well that was dug by Kobodaishi. There are a lot of hot springs around the mountain including Ikaho Hot Springs.”
See also 鬼丸大将1巻 By 手塚治虫 for a charming account of the legend of General Onimaru, Haruna and the giant Daidarabotchi