Shikoku Karst Overview
Stretching approximately 25 kilometers along the border of Ehime and Kochi prefectures, Shikoku Karst is one of Japan’s three major karst landscapes, alongside Akiyoshidai in Yamaguchi prefecture and Hiraodai in Fukuoka prefecture. Sitting at elevations between 1,000 and 1,500 meters above sea level, this sprawling highland plateau is often called the “Roof of Shikoku” and has earned a reputation as one of the most dramatic natural landscapes in western Japan.
The terrain is defined by exposed clusters of white limestone jutting out of rolling green meadows — a geological formation created when the limestone seabed of the ancient Nankai Trough was scraped by tectonic movement and gradually uplifted over millions of years. The result is a landscape of karrenfeld (flat limestone fields) and doline (bowl-shaped sinkholes) that gives the plateau an almost otherworldly quality, particularly when low clouds drift across the ridgeline. Designated a prefectural natural park in 1964, the area spans the municipalities of Kumakogen, Seiyo and Uchiko in Ehime, as well as Yusuhara and Tsuno in Kochi.
Three key areas draw the most visitors. The Tengu Highland (Tengu Kogen), at the plateau’s eastern end and its highest point at 1,485 meters, offers 360-degree panoramic views stretching from the peaks of the Ishizuchi mountain range to the north to the Pacific Ocean to the south on clear days. The Himezurudaira area in the center serves as the main tourist hub, with accommodation, campsites and observation points surrounded by pastureland. The Onogahara grasslands at the western end are known for their striking limestone outcrops and dairy farms, where cows graze freely from spring through autumn.
The route connecting these areas — Prefectural Route 383 — has been designated one of Japan’s 100 most scenic roads and is nicknamed Tenku no Michi, meaning “Road in the Sky.” At night, the plateau’s distance from any major urban center means virtually zero light pollution, making it one of the finest stargazing locations in Shikoku. The Milky Way is visible to the naked eye on clear summer nights.
Best Times To Visit Shikoku Karst
Spring brings fresh green grass and flowering rhododendrons across the surrounding Ogawamine mountain range, while summer offers the coolest temperatures in the region — a welcome respite from lowland heat — along with lush meadows and the clearest conditions for nighttime stargazing. This is also when cattle grazing is at its most picturesque, with cows dotting the white-and-green hillsides against bright blue skies.
Autumn, from October into early November, transforms the landscape with silver susuki (pampas grass) and vivid foliage across the mountain slopes. It is arguably the most dramatic season visually, with morning mist frequently filling the valleys below while the plateau itself sits above the cloud line — a phenomenon called “unkai,” or sea of clouds.
Weekdays outside of Golden Week and the summer holiday period are the least crowded times to visit.