Kirosan Observatory Park sits at the summit of Mount Kiro at an elevation of 301.1 meters on the southern tip of Oshima Island in Imabari, Ehime Prefecture. The park is designated as part of the Seto Inland Sea National Park and has become recognized as one of the premier viewpoints along the famous Shimanami Kaido, the scenic route connecting Hiroshima Prefecture on Honshu to Ehime Prefecture on Shikoku.
The observatory's most distinctive feature is its architectural design by Kengo Kuma, the renowned architect and winner of the Pritzker Architecture Prize. The observation deck is deliberately integrated into the mountaintop and concealed among trees to maintain the natural landscape. Its unique pathways and varying deck heights create a maze-like structure that offers different perspectives at each level, providing a complete 360-degree panoramic view of the surrounding seascape.
From the observation platform, visitors can view the Kurushima Kaikyo Bridge, the world's first triple suspension bridge, spanning the Kurushima Strait below. The bridge, with a total length exceeding 4,000 meters, connects Oshima to the main island of Shikoku. On clear days, the view extends to Mount Ishizuchi, the highest peak in western Japan. The park is particularly popular at sunset when the sky transforms into shades of orange, and at night when the illuminated bridge creates a spectacular display against the Imabari cityscape.
The observatory offers both daytime and nighttime viewing experiences. During daylight hours, visitors can appreciate the contrast between the blue waters of the Seto Inland Sea, the white suspension bridge, and the green islands scattered throughout the seascape. The tidal currents of the Kurushima Strait, recognized as one of Japan's three fastest currents, can be observed from above. A small kiosk near the entrance sells refreshments and souvenirs.
The park is accessible by car, located approximately 15 minutes from Oshima Kita Interchange on the Setouchi Shimanami Kaido expressway. Parking is available with space for 18 ordinary vehicles. For those traveling from Imabari, the drive takes approximately 10 minutes from Imabari Interchange via Oshima Minami Interchange.
Cyclists frequently visit the park, though the climb to the summit requires good physical fitness given the elevation gain of over 300 meters. Both admission and parking are free, and the park is open 24 hours year-round. Public transportation is limited, with the nearest bus stop requiring approximately a two-hour walk to reach the observatory.
