Kozenji Temple is a historic Buddhist temple located in Tamba City, Hyogo Prefecture. Its mountain name is Daibaisan, and it belongs to the Soto school of Zen Buddhism, holding a distinguished status within the tradition. The temple’s principal object of worship is Shakyamuni Buddha, a statue said to have been created by a Buddhist sculptor named Kasuga.
Kozenji is designated as part of a National Historic Site and is widely known as the birthplace of Kasuga no Tsubone, one of the most influential women of the early Edo period. With its surviving castle-like stone walls, water-filled moat, and historical buildings, the temple offers a fascinating glimpse into Japan’s feudal past.
Kozenji stands on the site of the lower residence, or shimoyakata, of Kuroi Castle, a mountain fortress that played an important role during Japan’s Sengoku period (approximately the mid-15th to late 16th century).
After Akechi Mitsuhide conquered the Tamba region, the castle’s former residential grounds became associated with his retainer, Saito Toshimitsu. The temple was subsequently established on this historic site.
Several features of the former fortified residence remain visible today, including the water-filled Shichikenbori Moat in front of the temple’s tower gate, tall stone walls, and white-plastered earthen walls. These structures preserve the atmosphere of a medieval Japanese castle residence.
Kozenji and the mountain fortress above it are included in the National Historic Site designation for the Kuroi Castle Ruins, reflecting the area’s importance in Japanese military and architectural history.
The predecessor of Kozenji was a temple called Johrinsan Seiganji, which stood approximately 150 meters downhill from the present site. During a military campaign in which Naito Munekatsu, lord of Yagi Castle, attacked Kuroi Castle, Seiganji was destroyed by fire.
The former temple area was known as Terayashiki, meaning a temple compound. Nine temples once stood there, forming a religious district associated with Kuroi Castle.
Ogino Naomasa, also known as Akai Naomasa and the lord of Kuroi Castle, helped rebuild the destroyed temples. Through the construction of halls and other religious buildings, the area gradually recovered from the devastation of war.
In 1626, approximately 50 years after the fall of Kuroi Castle, the temple was relocated to its present site on the former lower-residence grounds.
During this transition, its mountain name changed from Johrinsan to Daibaisan, its Buddhist denomination changed from Shingon to Soto Zen, and its name changed from Seiganji to Kozenji. The temple’s foundation is traditionally attributed to Ogino Naomasa.
The tall stone walls and water-filled moat are believed to incorporate surviving structures from the former castle residence. These features make Kozenji particularly valuable as a place where visitors can observe the relationship between a Buddhist temple and the remains of a medieval fortress.
Kozenji is closely associated with Saito Toshimitsu, a retainer of Akechi Mitsuhide, who governed the area after Kuroi Castle fell to Mitsuhide’s forces.
Between 1579 and 1581, Toshimitsu is believed to have administered this area while traveling between Kuroi Castle and Kameyama Castle. In 1579, his daughter Ofuku was born here.
Ofuku later became known as Kasuga no Tsubone, the wet nurse of Tokugawa Iemitsu, the third shogun of the Tokugawa shogunate. She became a powerful figure in the shogun’s household and played an important role in shaping the organization and traditions of the inner quarters of Edo Castle, known as the Ooku.
A genealogical record of the Inaba family, known as the Inaba-ke Gokei-zu, refers to Kasuga no Tsubone’s birthplace in the Kasugai area of Hikami District, in former Tamba Province. This account supports the traditional identification of Kozenji’s grounds as her birthplace.
One of Kozenji’s most striking features is Shichikenbori, a water-filled moat extending approximately 80 meters along the temple grounds.
The stone walls rise about five meters and were constructed primarily using the nozurazumi technique, in which naturally shaped stones are fitted together without extensive cutting. This method is also seen in the remains of Kuroi Castle. Some sections feature carefully cut and fitted stones, suggesting later repairs or alterations.
Together, the moat and stone walls give the temple an unusual fortified appearance and provide valuable clues to the layout of the former castle residence.
The temple’s tower gate, or romon, was relocated from Chigenji Temple in Miyazu City. Its original construction date is unknown, although historical records indicate that it underwent repairs during the Genroku era (1688–1704).
With its traditional architecture and commanding presence, the gate forms an impressive entrance to the temple grounds.
The bell tower is traditionally attributed to Naoyoshi, the son of Akai Naomasa, who is said to have built it to honor his ancestors. The present structure was reconstructed in 1913, during the Taisho period.
A stone known as Ofuku Koshikake-ishi, or Ofuku’s Sitting Stone, is preserved within the temple grounds. According to local tradition, Ofuku sat and played on this stone when she was a young child.
Another historical feature is a well known as Ofuku Ubuyu no Ido, traditionally said to have supplied the water used for Ofuku’s first bath after birth. The well is approximately 1.7 meters deep and remains an important part of the temple’s local heritage.
Kozenji Temple offers much more than a traditional Buddhist temple experience. Its surviving moat and stone walls reveal its connection to Kuroi Castle, while its association with Kasuga no Tsubone provides a personal link to the political and cultural history of the Tokugawa shogunate.
Visitors can explore the temple’s historic architecture, discover stories passed down through generations, and appreciate the quiet atmosphere of this site in the Tamba region. For travelers interested in samurai history, Japanese castles, and the lives of influential historical figures, Kozenji is a rewarding destination.
Kozenji Temple is approximately a 10-minute walk from Kuroi Station on the JR Fukuchiyama Line.
From Kasuga Interchange on the Maizuru-Wakasa Expressway, follow National Route 175 toward the temple.