Ashiu Forest 2026: Kyoto’s Primeval Woods You Can Only Hike with a Guide

Kyoto · Forests & hiking

By Nobu · Updated June 2026 · From a guided summer trek, verified against the Kyoto University Ashiu Forest and the certified guide organisations

Ashiu is one of western Japan’s last great primeval forests — a cool-temperate woodland at the source of the 146-kilometre Yura River — and you can only walk into it on a guided tour with a Kyoto University-certified group, from about ¥11,000 per person, with tours running mostly between April and November.

I’ve hiked a lot of Japanese mountains, and almost all of them you can just turn up and climb. Ashiu is different. It’s a research forest run by Kyoto University, two hours north of the city in the Tamba highlands, and the gate is closed to anyone without a certified guide. That sounds like a hassle until you’re standing in it: trees that have never been cut, a stream you can drink from, an old timber railway disappearing into the green, and a guide who can tell you the name of every plant on a numbered tag. This is how to actually visit — the rules, the route I walked, what to pack, and the leeches nobody warns you about.

What Ashiu actually is

Ashiu (芦生) is a primeval forest at the headwaters of the Yura River, in the Tamba highlands of northern Kyoto Prefecture. It’s one of the largest natural cool-temperate forests left in western Japan, and since 1921 it has been a research forest of Kyoto University — which is exactly why it survived. While the hills around it were logged, this valley was studied and left mostly alone, so you get old beech, giant katsura and horse-chestnut, and an understorey that hasn’t been tidied for human visitors. In 2016 the wider area was designated the Kyoto Tamba Kogen Quasi-National Park.

It is also, quietly, a working scientific site. Trees carry little numbered survey tags, plots are marked, and your guide reads the forest like a catalogue — this one’s a kihada, that hollow is where a bear sleeps. It’s the opposite of a manicured garden, and that’s the whole appeal.

Why you can only go with a guide

Because it’s a research forest, not a park — entry is restricted, and the only legitimate way in for a visitor is a tour run by one of four guide organisations certified by Kyoto University. You cannot drive in, park, and wander; there’s no casual day-ticket. You book a tour, the guide handles the entry permit, and you go in as a small group.

It’s worth doing properly rather than resenting it. The certified groups — among them the Ashiu Moribito Association, Ashiu Yama-no-ie, and the Miyama Nature & Culture Village (Kajika-sō) — run regular and custom treks, usually with lunch, from roughly ¥11,000 per person for a shorter group trek up to about ¥25,000 for a full-day tour, depending on the operator, length, and group size. Book ahead: popular dates in the fresh-green and autumn seasons fill early, and some run a booking window that closes well before the day.

The route I walked: Shimodani & Bunanoki Pass

I did the Shimodani–Bunanoki Pass course (下谷・ブナノキ峠), a roughly three-to-four-hour loop that’s a good middle option — real forest, real climbing, but not a full day on your feet. It threads two of the things Ashiu is famous for: the beech ridge up at the pass, and the giant trees down in the Shimodani valley.

There are longer courses too — the full Bunanoki Pass route combined with the Yura source can run closer to 7 km and six hours, including the minibus transfer in — and gentler ones that stay low in Shimodani. Tell the guide org what you’re up for.

The old forest railway

One of the strangest, best things in Ashiu is the narrow-gauge railway. It was laid to haul timber and supplies out of the forest, and stretches of the track and its little carts are still here, rusting quietly into the moss. Part of the walk in follows the old rail bed along the river, and it gives the place an oddly tender, abandoned feeling — a reminder that even a forest this wild has a human history.

When to go — and the leeches

Tours run from March to December, and there are two headline seasons: fresh green in May–June, when the new leaves almost glow, and autumn colour in late October–November, when the beech and maple turn. I went in summer, which is lush and quiet and a little wild — and which brings the one thing you should plan for.

How to get there

Ashiu sits above the village of Miyama, in Nantan City, in the far north of Kyoto Prefecture. The honest answer is that you want a car: public transport into this part of the Tamba highlands is sparse and slow, and most guide tours meet at a trailhead or lodge you can’t easily reach by bus.

1. By car: roughly 1.5–2 hours from Kyoto city, via Route 162 (the Shūzan Kaidō) and Miyama. Your guide org confirms the exact meeting point.
2. Without a car: some tours arrange pickups, or you can bus to Miyama and coordinate with the guide — ask when you book. It’s doable, but it’s the hard way.
3. The Ashiu Road Park on the approach is a handy roadside stop to regroup before the forest.

If you’re building a rural-Kyoto trip around it, Ashiu pairs naturally with other quiet corners north and west of the city — see our guides to Kameoka and the Ine boat houses on the Sea of Japan coast that this very river runs toward.

What to pack

This is a real forest walk on uneven, often wet ground — not a stroll. The guide supplies the local knowledge; you supply the kit. Here’s what I’d bring, all on Amazon Japan so you can have it sent to your Kyoto hotel before you head north.

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Where to stay

The smart move is to stay a night in Miyama or the wider Nantan area so you’re not driving two hours before a morning tour. Miyama is lovely in its own right — it’s the village of thatched-roof farmhouses — and rural Kyoto inns are exactly where Rakuten Travel’s inventory beats the big international sites.

No car? You’ll want one for this corner of Kyoto — compare rental cars or look at Rakuten’s rental option for a day up north.

For readers from Southeast Asia

If you’ve done Kyoto’s temples and want the complete opposite — cool, green, empty — Ashiu is the antidote, though it takes a little planning from Singapore, Bangkok, KL or Jakarta.

Frequently asked questions

Ashiu is the rare place in Japan that you have to earn a little — book ahead, drive up, hand yourself over to a guide. What you get back is a forest the way it was before any of the temples in Kyoto were built: uncut, unhurried, and almost entirely your group’s for the morning. Go in fresh green or autumn if you can, pack for leeches if you can’t, and drink from the river while you’re there.

Sources: Kyoto University Ashiu Forest Research Station; the certified Ashiu guide organisations (Ashiu Moribito Association, Ashiu Yama-no-ie, Miyama Nature & Culture Village) and Miyama tourism information; Kyoto Tamba Kogen Quasi-National Park. Tour prices, dates and access can change — confirm with a certified guide organisation before you plan.