Long before the first Mt. Fuji 100 in 2012 (known as UTMF back then), runners in Japan were testing their mettle against legendary courses like the Mt. Fuji Climbing Race (founded in 1913, a challenging 21k with a brutal 3,000 meters of elevation gain), the Hasetsune Cup (founded in 1993, a demanding 70k with over 4,200 meters of elevation gain) and the awe-inspiring Trans Japan Alps Race (founded in 2002, a mind-boggling 415k course with a staggering 27,000 meters of elevation gain).
Before the ultra-trail scene exploded in the 2010s, most Japanese trail races in the late 90s and early 2000s focused on distances between 20k and 70k and were often called “mountain marathons” or “climbing competitions” as the term “trail running” wasn’t established in Japan quite yet. While road ultras in Japan (like the famed 100k Lake Saroma ultramarathon, established in 1987) thrived at this time, trail ultras remained rare. However, as European and North American 100k+ trail races gained popularity, Japanese runners craved a similar challenge. This led to the emergence of domestic 100k trail races like the OSJ Ontake (100k) formed in 2008 and the Shinetsu Five Mountains Trail (110k) formed in 2009.
The 100-Mile Boom and UTMF’s Global Ambitions
By the early 2010s, the global trail running scene was surging, with the 100-mile distance becoming the gold standard for elite competition. Races like Western States, UTMB and Hardrock 100 were pushing the sport’s boundaries. Japan wasn’t immune to this trend. In 2012, the country witnessed a landmark event—the inaugural UTMF, Japan’s first open-field 100-mile trail race. Over 850 runners took the starting line, instantly establishing UTMF as a major player on the global stage.
It’s worth noting that the previously mentioned OSJ group was already flirting with the 100-mile format. Their 2011 Ontake race offered a limited 100-mile option for qualifiers, and the now-defunct OSJ Yatsugatake Super Trail also included a 100-mile course in the fall of 2012.
From the outset, UTMF’s ambitions extended far beyond Japan. The focus on the global stage undeniably propelled UTMF’s rise as a coveted “bucket list” race for runners worldwide. Furthermore, the success of UTMF inspired the emergence of other 100-mile races across Japan in the years to come, solidifying the country’s position as a major player in the diverse world of ultra-trail running.
The 2024 Mt. Fuji 100: Back in the Spotlight
After a period of relative international quietude, the 2024 Mt. Fuji 100 roared back into the spotlight. First and foremost, it was because of its inclusion in the prestigious World Trail Majors.
Personally, participating in the Mt. Fuji 100 festivities felt like a dream come true. As a dedicated runner for only a few years, balancing a demanding full-time job and a bustling family life with two young children, exploring races beyond the Kanto region (think Tokyo and the surrounding prefectures) was often a challenge. However, over the past year, I had steadily built my experience in mountain trail races, conquering distances ranging from 15k to over 100k. The 2024 Mt. Fuji 100, attracting the world’s elite trail runners, held an undeniable allure. While initially unsure about tackling the full 100-mile course, the 70k Kai course ultimately proved to be the perfect fit for my schedule and family commitments.
For those unfamiliar, the Kai course is the shorter option at the Mt. Fuji 100, clocking in at roughly 70k with 3,500 meters of elevation gain and a generous 21-hour cutoff (compared to the 100-miler’s 44.5-hour cutoff). It essentially picks up where the 100-mile runners get drop bag access at aid station four (around 97k). Overall, Kai features steeper and more frequent climbs than the front half of the 100-mile course. Both races began at midnight, separated by 24 hours, creating a unique dynamic as runners from both distances shared the course for a significant portion of time.
Neither the Fuji 100 nor Kai had ever featured a midnight start before 2024. While some advantages exist, like potentially cooler temperatures for certain sections, the overall consensus, including my own experience, suggests this adds to the race’s difficulty. With the Fuji 100 being a major “A” race for many international competitors, a well-rested and prepared starting state seems crucial for success. Press releases indicated runners from over 34 countries participated in 2024, highlighting the race’s global appeal. For the 100-mile runners, strategically planned pre-race rest and accommodation near the venue become essential for optimal performance. Options like capsule hotels with nap facilities and race-day shuttle services cater to this need.
For my trip from northern Chiba prefecture, I opted for a chartered bus departing from Shinjuku station on the Friday afternoon before the race. This 2-hour journey ensured I arrived with ample time to check in (which only took 30 minutes), get settled and then face the long wait before the midnight start.
Hitting the Ground Running
The 70k Kai course, mirroring the full Fuji experience, presented a diverse terrain of trails, climbs, and descents. From smooth singletrack to rocky ascents requiring near-vertical scrambles, the route promised a demanding adventure. The first 5k, however, were a welcome reprieve—a road section where runners could stretch their legs. My friend, a Kai veteran, advised pushing the pace early to avoid getting stuck behind a pack on the technical trails ahead. While I wouldn’t normally go out this hard so early in a long race (risking bonking later), knowing the upcoming climbs would favor hiking and walking, I embraced this strategy.
Photo © Fuji Hakone Izu Trail Support – Gran Canaria World Trail Majors
Milestone by Milestone
With Kai’s four aid stations, I mapped out the course in five segments, using each one as a mini-goal and a chance to mentally recharge. The initial section, despite being one of the longest, proved to be the easiest. Relatively flat roads and close proximity of runners under the darkness made navigating a breeze. However, as the kilometers ticked by, the terrain steepened, runners spread out and the distinct presence of the blue-bibbed 100-mile runners became evident. They had already been on the course for over 24 hours and nearly 100k by the time our paths merged. I won’t forget some of the envious looks I received from the 100-mile runners as they struggled to jog while I bombed downhills effortlessly early-on in the Kai course.
Night Passages and Scenic Rewards
For the first 6–7 hours, I ran alongside my friend, enjoying conversation and the relatively smooth trails under the cool night sky. While the almost constant cloud cover through my race obscured some of the majestic views of Mt. Fuji I’d anticipated, it also prevented overheating, a fair trade-off in my mind. Despite the sleep deprivation I was dealing with from the midnight start, tackling the first half of the course at night, which I perceived as less challenging, turned out to be a positive. From section three onward, the character of the course shifted. Trails became steeper, climbs more demanding and rock faces increasingly daunting. Conquering these sections in daylight likely proved to be safer and faster than having to navigate them in the dark (as would have been the case in years past).
Fueling through the night
A midnight start presents a unique fueling challenge for both the 100-mile and 70k races. Unlike my usual routine, in which I avoid eating between midnight and 6 a.m., runners need to find a way to keep their bodies energized throughout this timeframe. While I personally struggled at times, I managed by packing a variety of snacks and gels and taking full advantage of the well-stocked aid stations. My pack overflowed with options like waffles, energy bars, pretzels, candy and caffeinated drinks to keep me awake and moving. The extra weight was a worthwhile trade-off for the flexibility it offered.
The aid stations along the Kai course were impressive, offering a delicious and diverse selection of food. Miso soup, rice balls, donuts, udon noodles, and of course, bananas, were some of the highlights.
Courtney The Queen Of Ultras. Photo © Fuji Hakone Izu Trail Support – Gran Canaria World Trail Majors
Conquering Kai
Mentally dividing Kai into five sections helped me navigate the course. The first section, featuring a significant portion of road running, eased me into the race. Section two marked the true beginning of the trail experience, while section three plunged us deep into the mountains with challenging climbs and descents. Sections four and five, however, proved to be the most demanding. Fatigue undoubtedly played a role in these sections, but each of these final two segments presented its own unique obstacles.
Emerging from the light woods surrounding Fuji Hokuroku Park, the finish line finally materialized. A surge of adrenaline propelled me into a sprint, a cherished tradition I wasn’t about to abandon. While others walked with triumphant smiles, I crossed the finish chute with a flourish, the goal line snapping taught as I broke the plane.
The inevitable post-race lull settled in, but this time, it was tinged with inspiration. The Mt. Fuji 100 and Kai are testaments to the spirit of ultra-trail running in Japan, uniting a passionate community from across the country and beyond. This 3,400-strong field, the largest I’d ever encountered, buzzed with international camaraderie, particularly with runners from neighboring Asian countries. My first foray into trail running in Shizuoka and Yamanashi prefectures left me yearning to explore more. Over 12 hours spent immersed in nature’s vast canvas solidified my love for this sport.