Nine peaks under one name — Kyushu's highest mainland mountain
Mt. Kuju is a volcanic range across Kuju, Taketa, and Yufu in Ōita Prefecture, and the name covers a nine-peak chain centered on Nakadake (1,791 m), the highest summit. Nakadake, Kyūsumi (1,786 m), Mitsumata, Taisen, Heiji, Inahoshi, Tengu-ga-jō, Hoshō, and Ōgi-ga-hana form the chain. The range sits at the heart of Aso-Kuju National Park, and Nakadake is the highest mountain on the Kyushu mainland (Mt. Miyanoura at 1,936 m on Yakushima is offshore). Kyūya Fukada included Kuju in Nihon Hyakumeizan as Kyushu's representative mountain group.
Kuju's appeal is in the geography of multiple independent volcanic peaks clustered together. From any summit, the others stand close enough to feel adjacent, and the Bōgatsuru wetland at the centre, a Ramsar-listed peat bog, forms a particularly fine composition for Kyushu mountain landscapes. To climb Kuju is not to tag a single summit but to walk a range of peaks plus the central wetland — the mountain area as a whole.
Makinoto Pass — the standard approach
The most standard route starts at Makinoto Pass (1,330 m). From Makinoto, the trail goes via Mt. Kutsukake, Nishi-Senrihama, and Kyūsumi-Wakare to Mt. Kyūsumi, then loops to Mt. Nakadake and Mt. Tengu-ga-jō. About 460 m of vertical, 5–6 hours total. A day-trip bagging the two highest peaks (Kyūsumi and Nakadake) — easily the entry-level Kuju route and the most popular.
The second main route starts at Chōjabaru (1,030 m) and crosses Amagaike Pass into Bōgatsuru, then uses Hokke-in Onsen Sansō as the base for each peak. From Chōjabaru to the hot-spring hut is about 3 hours; from there the trails fan out to Nakadake, Mt. Taisen, Mt. Heiji, and others. A two-night plan based out of Hokke-in Onsen Sansō, hitting several peaks across the days, is the deepest way to experience Kuju.
Bōgatsuru wetland — a Ramsar-listed bog
At the centre of the Kuju range lies the Bōgatsuru wetland, a high-elevation peat bog around 1,200 m that was designated a Ramsar Convention wetland in 2005. It sits in a basin surrounded by the nine peaks, with Hokke-in Onsen Sansō at its centre. From Bōgatsuru the peaks rise on all sides — one of Kyushu's most distinctive mountain compositions. It is also the setting of 'Bōgatsuru Sanka,' a folk song beloved among climbers.
From late May through June, the area blooms with Miyama-kirishima (Kyushu azalea), forming pink carpets across the slopes. Mt. Heiji's summit is one of Kyushu's premier Miyama-kirishima sites and draws climbers specifically for the flower window. Climbing Kuju is therefore not just peak-bagging — it is integrating the wetland and the seasonal flower bloom into a layered trip.
Hokke-in Onsen Sansō — a 1,303 m natural hot spring hut
At the centre of the range, in the Bōgatsuru wetland, stands Hokke-in Onsen Sansō — Kyushu's highest natural-hot-spring mountain inn at 1,303 m. With a history dating back to the Edo period, it remains the key climber's base on the range. Capacity about 100, two-meal stays and day-use baths available. For two-night plans roaming the peaks from Bōgatsuru, two nights at Hokke-in Onsen Sansō is the standard structure.
Peak-season reservations should be made weeks ahead. Hokke-in Onsen Sansō is smaller than the Northern Alps or Yatsugatake major huts, but a natural hot-spring bath inside the mountain is essentially unique in Kyushu and forms one of the central reasons to climb Kuju. Climbing Kuju is at once standing on Kyushu's highest mainland peak and overnighting at the centre of a Ramsar-listed wetland.
Year-round climbing — season and gear
Kuju climbs year-round. The Miyama-kirishima bloom from late May into June is the busiest season; July–August is summer hiking; late October–November is autumn colour; December–March is bare-winter terrain. Winter brings snow to the summit zone and Kuju serves as a popular winter-climbing venue too. As one of the few Kyushu ranges with usable winter mountaineering conditions, it functions as a local training ground in the snow season.
Gear assumes a long day at 1,800 m. Fleece and a wind- and waterproof shell are not optional; mid-cut or higher boots; a 20 L day pack or 30 L+ overnight pack. Volcanic gas can vent near Nakadake and the Hoshō / Iō-yama area — check closure boundaries and volcanic alerts before leaving. Winter ascents require light crampons, a real winter shell, and spare insulation.
Sunrise from Hokke-in Onsen Sansō is a distinctive Kuju composition: Mt. Taisen and Mt. Heiji to the east, Kyūsumi and Nakadake to the south, Mt. Mitsumata to the west, the Bōgatsuru wetland to the north — you stand at the geographic centre of the range. The peaks rising above wetland morning fog is a uniquely Kyushu view. New-moon midsummer nights combine wetland darkness with 1,300 m clarity to give Kyushu's best-class stargazing.
Access from Yufuin, Ōita, and Kumamoto
Access runs from JR Bungo-Nakamura or Yufuin Station on the Kyūdai line by Kyushu Cross-Country Bus or Ōita Kōtsū to Makinoto Pass in 60–90 minutes. Chōjabaru is on the same bus route. By car, parking is available at both Makinoto Pass and Chōjabaru. The Yamanami Highway (Prefectural Route 11) is the main road serving the Kuju area, with access via the Aso outer rim from Kumamoto and via Yufuin or Beppu from the Ōita side.
From Tokyo, flights to Ōita Airport take about 100 minutes, then rental car or bus connections; alternatively, fly into Kumamoto Airport. From Fukuoka, the expressway reaches Kuju in about 2.5 hours; from Beppu Onsen it is about an hour. Kuju is Kyushu's highest mainland peak yet reachable to its trailhead by road — a major reason for its sustained popularity. After descent, Beppu Onsen, Yufuin Onsen, Nagayu Onsen, and Sujiyu Onsen all serve as rinse-off destinations. Climbing Kuju is at once climbing Kyushu's highest mainland peak and soaking in a hot spring in the middle of a Ramsar wetland — a uniquely Kyushu density of experience.
