Gozen Shimizu Spring is a natural freshwater spring situated on the outskirts of the Kasugayama Castle Site. The spring was originally located on the grounds of the nearby Hakusan Shrine; although the location it is tapped has changed, its source remains the same.

Mt. Kasugayama has several spring water sources. This was known when Kasugayama Castle was in use during the sixteenth century, and excavations and remains show that multiple wells were dug into the mountain within the former castle grounds. As the main enclosure of the castle was situated 180 meters above sea level, there were no streams providing running water, but the existence of ample well water made the location suitable for a fortress.

Some wells on Kasugayama were dug by hand, penetrating into the bedrock to reach groundwater, while others were cisterns for storing rainwater. Archaeological excavations have uncovered traces of vertical and horizontal wells as well as reservoirs, which supplied water for drinking and daily use. In the event of a siege, a ready supply of fresh water offered a significant strategic advantage.

Uesugi Kenshin (1530–1578), the lord of Kasugayama Castle, and his troops are said to have drunk and collected water from the Gozen Shimizu spring before heading into battle. The current site of the spring was created in 2004 and is regularly maintained by local residents. The water is said to be especially suited for preparing tea and coffee, and the spring has been designated a “famous spring” of Niigata Prefecture.