Senninzuka Jogaike Pond is a scenic irrigation pond in Nanakubo, Iijima Town, Kamiina District, Nagano Prefecture. Located within the Central Alps National Park, the pond is surrounded by beautiful mountain scenery and seasonal nature.
The pond was constructed in 1934, using the dry moat of Kitayama Castle, also known as Funayama Castle, which was built during Japan’s Warring States period. Its origins therefore reach back much further than the present pond itself.
After its construction, Senninzuka Jogaike became an important irrigation reservoir designed to warm water for agriculture. It has helped provide water for approximately 200 hectares of rice paddies downstream, supporting local agriculture for generations.
In 2010, the pond was selected as one of Japan’s 100 Best Irrigation Ponds by the Ministry of Agriculture, Forestry and Fisheries, recognizing its historical, agricultural, and scenic value.
The area has long been known as Senninzuka, a name associated with a tragic story from the age of samurai.
About 800 years ago, the Kaminuma family, retainers of the lord of Funayama Castle, is said to have built Kitayama Castle and governed the surrounding area.
In February 1582, Oda Nobutada led an attack into the Ina region. Kitayama Castle, defended by Kaminuma Sakon, eventually fell after fierce fighting.
According to local tradition, the remains and weapons of many warriors who died in the battle were buried here. The place subsequently came to be known as Senninzuka, literally suggesting a mound associated with a thousand people.
After the war, epidemics repeatedly spread through the area. Local people feared that the spirits of those who had died in battle were causing misfortune, and in 1844 they erected the Monument of Senkyunin Doji to honor and console the deceased.
Since then, memorial ceremonies have traditionally been held twice a year, in spring and autumn. People from the surrounding community continue to gather and quietly pray at the monument.
Because of this history, the area around Senninzuka Jogaike is more than an agricultural facility. It is also respected as a place of remembrance, prayer, and spiritual consolation.
Senninzuka Jogaike was specifically designed as a warm-water irrigation reservoir. Water is taken from the Yodagiri River and its tributaries and stored in the pond before being distributed to farmland.
The rivers flowing from the Central Alps carry very cold water, which is not ideal for growing rice. By allowing the water to remain in the pond, its temperature can rise before it is sent to the rice fields.
This system helped improve rice yields in the surrounding agricultural area and contributed significantly to the development of local farming. Even today, the pond remains an essential source of irrigation for approximately 200 hectares of rice fields.
The landscape around the pond changes beautifully throughout the year. In spring, thousands of cherry trees bloom around the area, creating a spectacular setting for enjoying the flowers.
Azaleas and hydrangeas add seasonal color along the waterfront, while autumn brings vivid foliage reflected in the quiet surface of the pond.
The area is also visited by many wild birds, including swallows and great cormorants, making it a pleasant destination for birdwatching. Surrounded by mountains, trees, and water, visitors can enjoy a peaceful break close to nature.
Senninzuka Park has been developed around the pond, providing facilities for outdoor recreation. The park includes a campground and a mallet golf course, making the area suitable for both relaxing visits and longer stays.
Spring is a popular season for cherry blossom viewing, summer is ideal for camping, and autumn attracts visitors with its colorful foliage. The park offers opportunities to enjoy the landscape in different ways throughout the year.
On clear days, visitors can also enjoy expansive views of the Central Alps and Southern Alps. The combination of the tranquil pond and surrounding mountain ranges creates an impressive landscape.
Address: Nanakubo, Iijima Town, Kamiina District, Nagano Prefecture
The nearest railway station is Nanakubo Station on the JR Iida Line. From the station, the pond can be reached on foot or by car.
By road, use Nagano Prefectural Route 220, Senninzuka Park Line.
Senninzuka Jogaike Pond quietly preserves the history of the Warring States period while continuing to serve the everyday lives of local people.
The pond’s calm waters reflect the surrounding Alps, while beneath the peaceful scenery lies a story of samurai battles, memorial traditions, and the development of agriculture in the Ina Valley.
For travelers exploring the Iijima and Ina areas, Senninzuka Jogaike offers a different kind of sightseeing experience. Here, history, local traditions, agriculture, and the natural landscape exist together in one peaceful setting.
A visit to the pond provides not only beautiful views but also an opportunity to appreciate the history and traditions that local communities have preserved for generations.