The story begins in 1427, when a Soto Zen temple called Kojakuji was founded in the remains of the Asuke clan's former residence, tucked into the folds of Iimori-yama. Two centuries later, in 1634, the temple's eleventh head priest, Kazuhisa Sanei, planted maple and cedar trees along the approach from the Tomoe River up to the temple grounds. It was an act of devotion that transformed a riverbank into a cathedral of color. Local residents followed his example over the generations, adding trees along both banks of the river and up the flanks of 254-meter Iimori-yama. Today, eleven distinct varieties of maple grow here -- some blazing crimson, others fading to pale gold, a few holding stubbornly to green while their neighbors burn -- creating a layered tapestry that shifts daily through the season.

The maples of Korankei typically reach full color between mid-November and late November, and the timing is everything. Arrive too early and the canopy is still tinged with summer green. Arrive too late and bare branches scrape a gray sky. But catch the peak, and the gorge becomes almost hallucinatory in its intensity. From the main entrance, a tunnel of towering maples draws visitors deeper into the valley toward the Taigetsukyo Bridge, the arched span that has served as Korankei's visual symbol since 1953. Nearby stands the Goshiki-Momiji, a single remarkable maple tree whose leaves display five different colors simultaneously -- a natural curiosity that draws photographers who crouch and angle for the shot that captures all five hues on a single branch. The annual Momiji Festival fills November with ceremonies, parades, and food stalls, while after dark, illumination transforms the canopy into something otherworldly, the leaves glowing against black sky and their reflections trembling on the surface of the Tomoe River.

Beyond the maples, Asuke itself is worth the visit. This former post town on the old Inakaido highway retains a quiet, unhurried character that the Toyota City sprawl to the south has not reached. The Sanshu Asuke Yashiki, a cluster of traditional thatched-roof buildings near the gorge entrance, preserves local crafts -- charcoal-making, paper-dyeing, bamboo weaving -- as living demonstrations rather than museum displays. The Kojakuji Temple that started it all still stands within the gorge, its Zen hall dating to the late Edo period. A fifteen-minute climb up Iimori-yama leads to an observatory at the summit that rewards the effort with sweeping views across the valley and surrounding mountains. The observatory was dedicated in 1987 to mark the visit of Operation Raleigh youth venturers during the program's Japan phase -- an unexpected international footnote in this deeply local landscape.

Korankei's popularity creates a paradox familiar to anyone who has visited Japan's most celebrated seasonal spots: the very beauty that draws people also draws traffic. During peak autumn weekends, National Route 153 through the center of Asuke clogs for roughly ten kilometers. A bypass road partially opened in 2008 has eased the congestion somewhat, routing through-traffic around the town center. For those without cars, Meitetsu Bus runs a roughly sixty-five-minute service from Higashi-Okazaki Station directly to the gorge. But the crowds are part of the experience -- families sharing thermoses of tea on the riverbank, elderly couples pausing on the Taigetsukyo Bridge to photograph the same view they have photographed every November for decades, children chasing fallen leaves along the water's edge. Korankei is not a hidden gem. It is a treasured one, tended for nearly four centuries by the same community that planted its first trees.