Mt. Dodairayama

Mt. Dodairayama stands at an elevation of 876 meters in the Okuchichibu Mountains of western Saitama Prefecture, approximately 100 kilometers from Tokyo. The mountain offers sweeping 360-degree views from its broad, grassy summit, including vistas toward the Chichibu Basin and, on clear days, Mt. Fuji. From the summit, visitors can see Mt. Tsukuba, Mt. Haruna, Mt. Ryokami, and on clear days, Tokyo's Skytree is visible.

The summit is home to the Dodaira Observatory, originally built in 1962 as part of the National Astronomical Observatory of Japan. The observatory houses a 91-centimeter reflecting telescope, which was the largest telescope made in Japan at the time of its installation. The facility has been repurposed as the Star and Green Creation Center, now serving primarily as a lodging facility with guest rooms converted from the original observatory building. Stargazing parties are held twice a month, typically on the second and fourth Friday nights, where visitors can observe through the telescope by advance reservation.

The mountain offers multiple visitor experiences beyond astronomy. A paragliding school operates from a large grassy field with spectacular views on the mountainside, attracting enthusiasts from across the Kanto region. The campground at the summit offers various accommodation options including tent sites, bungalows, log cabins, and Mongolian-style ger tents of various sizes. The location's minimal light pollution and elevated position make it particularly popular for stargazing and viewing city nightscapes after dark.

Several hiking trails lead to the summit, with the route from Shiraishi-shako bus stop being among the most accessible. The trails pass through plantation and natural forests, with some steep sections but generally well-maintained paths. Adjacent Mt. Kasayama (837 meters) is often climbed together with Mt. Dodairayama. Basic facilities including vending machines and water taps are available at the campground near the summit.

Access to Mt. Dodairayama begins at Ogawamachi Station on the Tobu Tojo Line, which connects to Ikebukuro in central Tokyo. From the south exit of Ogawamachi Station, take an Eagle bus to the Shiraishi-shako bus stop, a journey of approximately 35 minutes costing 650 yen. Winter is considered the ideal season for visiting due to the clearest air quality for viewing Mt. Fuji and the night sky. The mountain is free to access, though specific activities like telescope viewing sessions and campground accommodations require advance reservations and separate fees.