Tenzan Brewery is a famous brewery located in Ogi, Saga. The Gion River, which flows in front of the brewery, is said to be the birthplace of Genji fireflies and is one of the best places in Japan to view fireflies. Using the clear water of the bypassing stream, the brewery wants to craft sake that highlights the cereal flavors of the locally grown sake rice used.

The historic brewery buildings from the Meiji, Taisho, and Showa eras have been designated as national tangible registered cultural properties, and are also recognized as a Saga Prefecture Heritage Site. The main brand is "Tenzan", which is derived from Mt. Tenzan, the mountain peak to the north of the brewery. "Iwanokura" is the regional brand which is exclusive to Kyushu Island and "Shichida" is the brand exclusive to retailers and sake shops.