Guide
Ryo-oka Castle is a historic Japanese castle site located in Taguchi, Saku City, Nagano Prefecture. It served as the administrative center for the Ryo-oka Domain (Tanoguchi Domain) during the late Edo period. The site is famous for being one of only two pentagram-shaped star fortresses in Japan. Due to its extremely rare shape, it is often referred to as "Ryo-oka Goryokaku" (alongside the famous Goryokaku in Hokkaido) or "Kikyo Castle," named after the bellflower shape. Today, it is a designated National Historic Site where visitors can observe the architectural design principles of that era.
The castle was constructed during the late Edo period. While it was the base for the R-yo-oka Domain, it was officially known as the "Tanoguchi Jinya" because the status of its lord was not officially elevated to a full castle. The history following its abandonment is equally fascinating. Much of the castle grounds were repurposed for agriculture, and the former residence (Odaidokoro) was once used as a warehouse for farming tools. From 1875, the building even served as a local elementary school. This transition from a military stronghold to an agricultural and educational center reflects the local history. Interestingly, parts of the original castle buildings were dismantled and moved to nearby temples, shrines, and private homes, allowing the castle's architectural legacy to blend seamlessly into the local community.
The site preserves bastion-style stone walls, water moats, and the remains of the Odaidokoro. These structures are invaluable resources for understanding advanced fortification techniques of the time. To the northwest, visitors can observe the "Masugata" (gatehouse) remains, showcasing the meticulous defensive design. Because the site once functioned as a school, there are also historical traces related to its time as an educational facility. For a breathtaking view, the area around the former Taguchi Castle ruins to the north offers a panoramic perspective of the entire star-shaped layout. If you wish to capture the unique shape from above via drone, prior permission from the Saku City Hall is required.
Ryo-oka Castle is an open-air site that can be explored freely regardless of the season. Walking through the historical remains is a peaceful experience, especially during quieter hours when the atmosphere of the ancient fortress is most palpable. The observation area to the north provides a wonderful vantage point to see the castle's structure from a distance. While the surrounding landscape changes with the seasons, the historical charm of the ruins remains constant throughout the year.
There are several facilities nearby to deepen your understanding of the site. The "Saku City History Village Aino-kan," located near the Otemon gate, features valuable exhibits regarding Ryo-oka Castle. Additionally, if you make a prior reservation, you can tour the interior of the Odaidokoro to see the intricate details of the historical architecture and former living spaces. For those interested in local art, the "Kuramura Gozo Memorial Museum" nearby showcases the works of the famous local sculptor, providing a deeper connection to the region's culture.
The area surrounding the castle is rich with historical connections. For example, the former main hall (Daihiro) was moved to Jisho-ji Temple in Naruse, Saku City. The eastern gate was relocated to become the gate of Naritayama Yakushi-ji Temple, and other walls and gates were integrated into private residences along the path to Shinmai Sansha Shrine. These architectural fragments scattered throughout the local temples and homes create a unique cultural landscape. To the north, a path leads up approximately 160m to the site of the medieval Taguchi Castle.
When visiting the castle ruins, please keep the following in mind: