Kamuriki Mountain is a 1,252-meter-high mountain that straddles Chikuma City and Chikuhoku Village in Nagano Prefecture. Rising at the southwestern edge of the Nagano Basin, it is known for its beautiful natural scenery, fascinating geology, and deep connections with Japanese history, literature, and folklore.
The mountain has several names, including Kamuriki-yama, Kamuriki-yama (Kanmu-dake), Sarashina-yama, and Bōjō. Locally, it is also widely known as Obasute-yama or Ubasute-yama. These names reflect the many legends and cultural traditions that have developed around the mountain over centuries.
Kamuriki Mountain stands near the boundary between the central uplift zone of the northern Fossa Magna and its western sedimentary region. Its geological structure records a long history that began when this area was beneath the sea.
Sandstone, conglomerate, and tuff accumulated as layers of Tertiary rock on the ancient seafloor. Later, during the Quaternary period, volcanic activity produced an andesitic lava dome above these older layers. The summit is primarily composed of two-pyroxene andesite, a relatively resistant rock that has survived weathering and erosion to form the mountain’s distinctive rounded summit.
One of the most interesting geological features can be seen on the eastern slopes, where columnar joints are exposed. These naturally occurring structures were formed as volcanic rock cooled and contracted. Together with the lava dome, they provide a glimpse into the volcanic processes that shaped the region.
The geological features of Kamuriki Mountain also preserve evidence of the area’s turbulent geological past. Landslides and rockfalls associated with earthquakes have altered the mountain over time. The 1847 Zenkoji Earthquake, one of the major earthquakes to affect northern Nagano, is said to have caused collapses on the mountain.
Illustrations depicting the effects of this earthquake are preserved at the Sanada Treasure Museum in Nagano, providing a historical record of the dramatic changes caused by the disaster.
One of the mountain’s notable landmarks is Boko-daki Rock. The rock formation is believed to have undergone further collapse, particularly following the Matsushiro Earthquake Swarm. Although it is considerably smaller than it once was, the remaining rock continues to attract visitors and serves as a reminder of the powerful geological forces that have shaped Kamuriki Mountain.
Near the summit stands Kamuriki Shrine, marked by a torii gate and a small shrine building with a metal roof. The shrine enshrines Tsukuyomi-no-Mikoto, the Shinto deity associated with the moon. It was once worshipped as a Gongen shrine, reflecting the traditional Japanese connection between mountain worship and Buddhist-Shinto religious practices.
Every July, local parishioners gather at the summit for a traditional overnight devotional ceremony known as okomori. The event takes place in the mountain’s quiet natural setting, when fireflies can also be seen dancing around the summit.
A monument to the celebrated haiku poet Takaha Kyoshi also stands on the mountain. It bears the famous verse, “Sarashina ya, Obasute-yama no tsuki zo kore”, celebrating the moon over Obasute Mountain. Such literary associations have strengthened Kamuriki Mountain’s reputation as a place where nature, faith, and poetry meet.
The connection between Kamuriki Mountain and moon viewing dates back more than a thousand years. The mountain’s name appears in the Kokin Wakashū, an imperial anthology of Japanese poetry compiled in 905, demonstrating that the landscape was already celebrated during the Heian period.
The Imperial Palace in Kyoto was traditionally decorated with sliding-screen paintings depicting famous scenic places from throughout Japan. Kamuriki Mountain was among the landscapes associated with poetry about the moon, showing how widely its beauty was recognized beyond the local region.
One well-known poem begins with the words “Obasute no yama zo shigure…”. It is traditionally understood as having been composed while looking toward Kamuriki Mountain from the opposite bank of the Chikuma River. The poem captures the atmosphere of the mountain and the surrounding Sarashina countryside through changing weather and seasonal scenery.
Maps and illustrated geographical records from the Edo period sometimes depict Kamuriki Mountain and Obasute Mountain as separate mountains. This suggests that the two names were once clearly distinguished.
During the Meiji period, however, the efforts of Tsukada Masatake helped popularize the combined name “Kamuriki Mountain (Obasute Mountain)”. Over time, this terminology became deeply established in local culture and remains familiar today.
Several theories explain the origin of the name Kamuriki, including legends connected with Japanese mythology. One tradition relates the name to the story of Ame-no-Iwato, the heavenly rock cave where the sun goddess Amaterasu is said to have hidden herself.
According to the legend, the deity Tajikarao-no-Mikoto removed the great rock blocking the cave. Afterward, he is said to have stopped in this area and adjusted his crown, giving rise to the name Kamuriki, which can be associated with the idea of “adjusting a crown.”
The alternative name Sarashina-yama is traditionally explained by the mountain’s location near the center of the former Sarashina District. Sarashina was an important historical region of Shinano, the old name for present-day Nagano Prefecture, and the name appears frequently in classical Japanese poetry and literature.
The name Bōjō is said to have two possible associations. One relates to the rounded shape of the mountain, which resembles the shaved head of a Buddhist monk. Another tradition connects it with the mountain’s former role as a site for transmitting smoke signals, or noroshi, used to communicate over long distances.
The name Obasute-yama is closely associated with one of Japan’s best-known “abandoning the elderly” legends. In this story, an elderly person is taken into the mountains and left there so that the younger generation can survive.
The tale has appeared in classical works including the Yamato Monogatari and traditional Noh theater. Over the centuries, the story became closely associated with the Obasute name and had a lasting influence on the cultural image of the region.
For modern visitors, it is important to understand that the Obasute legend belongs to the world of folklore and literature. Its continuing significance lies not simply in the story itself, but in the way it has shaped the identity, poetry, and landscape traditions of the area.
One of the most beautiful landscapes associated with Kamuriki Mountain is the Obasute Rice Terraces in Yawata, Chikuma City. Built and maintained by generations of local farmers, these terraced fields spread across the mountain slopes and are renowned for their connection with moon viewing.
The landscape has long been known for the phenomenon called Tagoto-no-Tsuki, literally “the moon in every rice paddy.” During the rice-planting season, the terraces are filled with water. When the full moon rises, its reflection appears separately in the many small paddies, creating the illusion that each field contains its own moon.
The sight of the moon reflected in the water-filled terraces has been celebrated as a quintessential Japanese landscape for centuries. The combination of carefully cultivated fields, mountain scenery, and moonlight creates a uniquely poetic atmosphere that has inspired writers and artists throughout history.
The famous ukiyo-e artist Utagawa Hiroshige also depicted the landscape in his series One Hundred Famous Views in the Various Provinces (Rokujūyoshū Meisho Zue). His work helped preserve the image of Obasute’s moonlit terraces as one of Japan’s celebrated scenic views.
Kamuriki Mountain is much more than a mountain for hiking or enjoying panoramic scenery. Its geological formations tell the story of volcanic activity and earthquakes, while its summit shrine reflects centuries of mountain worship. Ancient poems, legends, and literary works have given the mountain a cultural significance that reaches far beyond Nagano.
At its foot, the Obasute Rice Terraces add another layer to this remarkable landscape. The reflections of the moon in the individual paddies symbolize the close relationship between agriculture, nature, and Japanese aesthetics.
For travelers exploring Chikuma City and northern Nagano, Kamuriki Mountain offers an opportunity to experience a landscape where ancient legends, sacred traditions, geology, classical poetry, and rural life remain closely intertwined. Visiting the mountain and the nearby Obasute terraces provides a deeper understanding of why this corner of Shinshu has been admired for more than a thousand years.