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A Complete Guide to the Koboyama Hike | Hadano Station to Tsurumaki-Onsen Station, Three Gentle Hours with Binoculars

2026.01.31

"I feel like walking a bit today." For weekends in that mood, the route I keep coming back to is the Koboyama hiking course in Hadano, Kanagawa. It runs from Hadano Station to Tsurumaki-Onsen Station, stringing together four small peaks — Sengenyama, Gongenyama, Koboyama and Azumayama — over 5.6 km and about three hours. Nothing about it asks you to hurry.

This post is a first-person account of the day, written for beginners and for anyone coming back to hiking after a while. Big views of Mount Fuji and Sagami Bay, and a new way of enjoying a mountain that I tried for the first time here: birdwatching with binoculars. I'm usually the one glancing at the clock and feeling rushed, so a day I genuinely spent slowly is worth recording.

Route overview (Hadano Station to Tsurumaki-Onsen Station, about 3 hours)

• Area: Hadano, Kanagawa Prefecture (the Koboyama Park hiking course)
• Route: Hadano Station → Kobo no Shimizu spring → Sengenyama → Gongenyama → Babamichi (the cherry-lined ridge) → Koboyama → Zenba Pass → Azumayama → Tsurumaki-Onsen Station
• Distance and time: About 5.6 km, roughly 3 hours in total
• Access: Start at Hadano Station on the Odakyu Odawara Line and finish at Tsurumaki-Onsen Station — station to station. There is also parking near each peak if you only want the views
• Difficulty: ★☆☆☆☆ to ★★☆☆☆ (beginner). Well-maintained stepped trails with a few steep sections and nothing dangerous
• Conditions on the day: The Hadano forecast said a high of 10°C and a low of -4°C — properly midwinter

Starting and finishing at a station means you never have to think about getting back to a car, which is a large part of why this route works so well. Toilets and benches are properly maintained along the way, so it's a safe choice for a first mountain.

From Hadano Station — filling a bottle at Kobo no Shimizu

The day starts at Hadano Station, and the first stop is Kobo no Shimizu, a spring near the station where anyone can take water. A local told me people come by for it now and then because it's good to drink, so I tried a mouthful. Cold and clean — it felt like a small piece of luck before the walking had even started.

Bottle filled, the hike begins. It's about 1.2 km from the station to the entrance of Koboyama Park; you walk out through a residential area and the park signs appear. From the trailhead it's a zigzag climb through trees. Some of the early sections are reasonably steep, but the steps are well built, so as long as you take them one at a time without rushing you'll be fine.

The clearing with a Mount Fuji view, and a new way to enjoy a walk

A little way up you come out at an open area with benches, and it's immediately pleasant. Turn around and Mount Fuji appears through a gap in the trees. Being able to sit on a bench and look at Fuji is a luxurious way to take a break.

This was also the first time I'd carried binoculars — a Kenko pair — up a mountain. They have some weight to them, but the clarity when you first look through made me say something out loud. Line them up roughly by eye, ease the focus across, and a small bird resolves in startling detail. "Lenses are incredible" came out of my mouth more than once.

Until now, my attention on a mountain went into climbing and looking at the view. With binoculars, roadside birds and distant townscapes become things to study, and your own walking pace slows down as a result. Adding one pair of binoculars to a low mountain creates a whole new game — that was my biggest discovery of the day.

Sengenyama and Gongenyama — an observation deck and a bird sanctuary

The first peak is Sengenyama. The teahouse at the top had a handwritten sign advertising mountain beer, and that kind of easygoing note is very low-mountain. The toilets are beautifully looked after and stocked with paper, which is genuinely reassuring for a beginner.

Then you drop onto a paved section, follow the signs for the "Forest Therapy Road," and reach the next peak, Gongenyama. There's a substantial observation deck here with views out to Sagami Bay and Mount Fuji — the best viewpoint on the whole route.

Gongenyama also has a bird sanctuary attached, which is exactly where the binoculars earn their place. Wait quietly and one small bird after another appears. I spent that stretch saying how cute they were and being very glad I'd brought the extra weight.

Along the cherry-lined Babamichi to Koboyama

The path from Gongenyama to Koboyama is Babamichi, a flat, easy ridge with cherry trees planted along both sides. It was bare winter when I walked it, but in spring it must become a tunnel of blossom. It's the kind of path that makes you decide to come back in April. There's a Genghis Khan grilled-lamb restaurant along the way too, though it was closed on the Monday I visited — saved for next time.

Eventually you reach Koboyama, the peak the whole course is named after. The summit is broad, with a temple bell and an old well known as Chichi no Ido, the "milk well," among other things to look at. There are plenty of benches, and it's a fine place to unwrap an onigiri and sit for a while.

The Koboyama viewing deck — from Tokyo Skytree to Enoshima

The thing not to miss on Koboyama is the viewing deck near the summit. The air was exceptionally clear on this day and the view ran a long way.

Looking hard from the deck I could pick out Tokyo Skytree, the Landmark Tower, the Yokohama Bay Bridge and Enoshima, with the Miura Peninsula running on to the Boso Peninsula behind them — the Kanto plain and the sea laid out as a single picture. The binoculars came out again here, and following one town after another, I lost track of time. The scale of it doesn't feel like a low mountain at all, and I was straightforwardly glad I'd made the climb.

What I wore: Montbell O.D. Pants Insulated

The piece I wanted to test on this hike was the Montbell O.D. Pants Insulated, which I reviewed in detail in an earlier video. When I bought them I assumed they'd be for town and for standing around waiting, but I wondered whether a low-elevation walk like this one might suit them.

The short version: on a day topping out around 10°C, on gentle terrain, they were comfortable with no real complaints. I never felt cold in the morning or on the trains, and on the steeper sections there was a brief moment of "slightly warm" that never tipped into overheating. On a serious climb they would definitely be too hot, so I'd keep them to low-mountain hiking. I run cold even by the standards of women I know, which is why they suited me; a lot of men would probably find them too warm. Take it as one data point for choosing your own insulation.

Over Azumayama to Tsurumaki-Onsen Station — protecting your knees on the descent

From Koboyama it's downhill toward Tsurumaki-Onsen Station, and the surroundings turn much more like a mountain trail here. At the Zenba Pass junction, a path branches off toward Takatoriyama and on to Oyama, about 9.5 km — a traverse I'd like to walk one day. We went toward Tsurumaki-Onsen.

What I concentrate on when descending is short, light steps to protect my knees. I try not to land heavily. Someone taught me this a while back and I've changed how I walk downhill ever since. This route has few big drops, so the load on my knees stayed light.

The last peak, Azumayama, has benches with a good view too. Take a break there and it's roughly 1 km to the station. Signs are posted at all the key junctions, so there's very little chance of getting lost.

One practical note: there are no toilets between Koboyama and Tsurumaki-Onsen Station. If that matters to you, use the ones at the Koboyama summit.

Afterwards: hot springs and food (watch out for Monday closures)

Half the appeal of a low mountain is what comes after. My plan was the day-use hot spring near the station, Kobo no Satoyu — except that it was Monday and closed. I didn't get to try the foot bath I'd been eyeing either.

Right next to it there's also a hot-spring tap where you can take home natural onsen water drawn from 1,000 m below Tsurumaki-Onsen (up to 4 litres per person). Someday I'll bring some back for the bath at home; that day, with the baths closed, I gave up on it.

For food I'd been aiming at Shirohige Shokudo, known for its omurice and pudding — also closed for lunch on Mondays, dinner service only. Mondays tend to be the day when the onsen and the restaurants close together, so check the day of the week if you want the full post-hike programme. I ended up in Ebina on the way home with fried oysters, in season in winter, as the day's reward. A hard squeeze of lemon and they were exactly right after a walk.

What I'd tell you about this route

Finishing the Koboyama course, the thought I came away with was that this is a mountain I'd happily walk often. The views are lovely, the trail is never too hard, and it runs station to station. I'd recommend it without hesitation to a first-timer, to someone returning after years away, or to anyone who simply wants to walk slowly.

I'm normally the person losing time on the climbs and getting anxious about it. This time, unusually, I never rushed. Mount Fuji and Sagami Bay, plus a new game in the form of birdwatching — that kind of unhurried margin is exactly what a low mountain gives you, and I love it.

So when you feel like walking just a little, think of Koboyama. I hope it makes your weekend slightly richer.

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