Lake Biwa 100: Racing a 100-Mile Ultra in Japan

Japan had been on my travel bucket list for years, so combining a trip with one of the country’s toughest 100-mile ultras felt like the perfect adventure.

The Lake Biwa 100 is a point-to-point ultra marathon through the rugged mountains east of Kyoto, eventually finishing on the sandy shores of Lake Biwa. Technical trails, huge climbs, heat, humidity and a completely different trail-running culture made it unlike any race I’d experienced in Europe.

I eventually finished 9th, although the race didn’t exactly go to plan.

Here’s what I learned from racing 100 miles through the mountains of Japan.

What Is the Lake Biwa 100?

The Lake Biwa 100 is a 100-mile trail race through the mountains surrounding Lake Biwa, Japan’s largest freshwater lake.

Unlike many European trail-running festivals, where several distances take place across the same weekend, Lake Biwa focuses entirely on the 100-mile race. It gives the whole event a real sense of occasion, with the organisers, volunteers and supporters all focused on one challenge.

The terrain is seriously tough too.

Technical ridges, steep climbs, roots, loose stones and long mountain sections make this much more than simply running 100 miles.

And then there’s the Japanese heat and humidity.

Finishing 9th at the Lake Biwa 100

The race itself was an unforgettable experience, although I made life considerably harder for myself towards the end. With around 40km remaining, I caught the race leader and eventual winner. I got a little excited.

Instead of sticking to my own pace, I pushed too hard trying to compete at the front. Eventually, the effort caught up with me. I completely blew up and went from racing for the lead to stumbling my way towards the finish.

It wasn’t quite the ending I’d imagined, but I held on to finish 9th overall. A pretty good lesson in why pacing still matters, even when you’ve been racing ultras for years.

Why Race a 100-Mile Ultra in Japan?

Japan had been a bucket-list destination for as long as I could remember. I love travelling somewhere that feels completely different from the UK, and racing gave me an opportunity to experience Japanese trail-running culture rather than simply visiting as a tourist.

The Lake Biwa 100 stood out because of its combination of beautiful mountain terrain, technical trails and strong competition. In some ways, the event felt similar to a major European ultra. The organisation was excellent and there was a strong atmosphere around the race.

In other ways, it couldn’t have felt more different.

Japanese Ultra Running Culture

One of the first things that struck me was the friendliness and mindfulness of the organisers. There was a real sense of community around the Lake Biwa 100. You could tell that the people involved genuinely cared about the runners and the event.

I was also surprised by just how mountainous Japan is. Much of the landscape is steep, dramatic and wild, making it an incredible place for trail running.

Japanese Ultra Marathon Aid Stations

Then there were the aid stations. Alongside the sports nutrition you’d expect at an ultra, there were noodles, rice balls and miso soup. The selection was incredible and added another distinctly Japanese element to the race.

The post-race celebration was taken just as seriously, with a huge BBQ on the beach during the awards ceremony. After 100 miles in the mountains, it was a pretty good way to finish.

Lake Biwa 100 Traditions, Kit and Bear Bells

There were a few things about racing in Japan that I definitely hadn’t encountered at European ultras. The mandatory kit list included items such as a bear bell and a specific toilet kit, both of which were surprisingly difficult to find back in the UK.

Luckily, some local runners at the race expo kindly lent me what I needed. There’s also an important Lake Biwa finish-line tradition. When you reach the lake, you jump in. Just remember to take your phone out of your pocket first.

Then there are the onsen, Japan’s traditional hot spring baths. Completely naked communal bathing isn’t something we’re particularly used to in the UK, but after running 100 miles through the mountains, they’re pretty incredible for relaxing afterwards.

How Tough Is the Lake Biwa 100 Course?

The Lake Biwa 100 trails were unlike anything I’d raced on before. The opening section is particularly technical, with short, sharp climbs and ridges.

The first 50km included around 4,500m of ascent and took me approximately eight and a half hours. That gives you some idea of how difficult the terrain is.

After that, the middle 50km becomes more runnable before the final marathon brings back the long, steep and technical climbs. Underfoot, there were countless tree roots and tiny loose stones, which made finding secure footing difficult.

It’s the sort of terrain where looking at distance alone tells you very little about how long a section is actually going to take.

Racing an Ultra in Japanese Heat and Humidity

One of the biggest differences compared with racing in the UK or Europe was the weather. The heat and humidity were noticeably higher than anything I’d previously raced in, and they ultimately played a significant role in how my race unfolded.

Looking back, I probably became dehydrated. Pushing too hard while not carrying quite enough water in humid conditions likely contributed to my collapse during the final stages.

It’s one of the biggest lessons I’d take from the race: when you’re competing somewhere with unfamiliar conditions, your normal hydration strategy might not be enough.

How I Fuelled the Lake Biwa 100

For my race nutrition, I used a combination of VOOM Pocket Rockets and VOOM Fusion Fuel throughout the Lake Biwa 100. I supplemented those with food from the aid stations, particularly Japanese rice balls.

My crew also managed to introduce something slightly less Japanese into proceedings: cheese sandwiches.

For an ultra of this length, having different textures and flavours available can be really useful. Sports nutrition provides an easy way of getting carbohydrates in while moving, while familiar real food can become particularly welcome as the hours add up.

My fuelling generally worked well. Hydration was where I could have done better.

The combination of humidity, hard racing and not carrying enough water eventually caught up with me.

The Challenge of Racing 100 Miles So Far From Home

Travelling halfway around the world to race brings challenges you don’t necessarily face at a European ultra. One of the biggest was that I couldn’t recce the Lake Biwa 100 course beforehand.

Instead, I relied heavily on YouTube videos and information from my crew to understand what was coming. Then there was the jet lag.

If I return, hopefully in 2028, I’d arrive earlier and give myself more time to properly adjust to the time zone. I’ve normally been fine running through a single night, but this time the tiredness was on another level. At points I was falling asleep while hiking.

There may even have been a couple of dirt naps.

Running Through the Japanese Mountains at Night

There were also moments where it became very obvious that I was racing a long way from home. Running alone through the mountains at night and repeatedly seeing bear warning signs certainly kept me awake.

Seeing pairs of eyes staring back from the trees wasn’t particularly reassuring either. Thankfully, the animals I actually encountered turned out to be deer and wild boar. Still enough to get the heart rate up.

Incredible Support in the Japanese Mountains

The local support was another highlight. There were people cheering runners on from incredibly remote sections of the mountains, particularly early in the race.

Some of them must have spent a significant amount of time getting into position just to support the runners. When you’re deep into a 100-mile race, those moments can make a huge difference.

What European Ultra Runners Can Learn From Japan

One thing that really stood out was the determination of the Japanese runners. For such a difficult 100-mile race, the DNF rate seemed impressively low.

Even when things weren’t going well, there appeared to be a real determination among the local runners to keep grinding away and reach the finish. There was a quiet resilience to the way people approached the race that I really admired.

What I Learned From Racing the Lake Biwa 100

I travelled to Japan hoping for an adventure, and the Lake Biwa 100 definitely delivered. Finishing ninth was a result I’m proud of, even if part of me wonders what might have happened if I hadn’t got carried away when I caught the leader with 40km remaining.

But that’s ultra running.

The technical trails, huge climbs, humidity, Japanese aid stations, incredible volunteers and completely different culture made this much more than another 100-mile race.

I learned some valuable lessons too: respect unfamiliar conditions, carry enough water, give yourself time to adapt to the time zone and, perhaps most importantly, don’t completely abandon your pacing strategy just because you’ve caught the race leader.

Would I go back?

Absolutely.

Hopefully I’ll be standing on the start line again in 2028.

And next time, I’ll know where to buy a bear bell.