I Looked Into Maruyama Kosen Ryokan

This blog has been steadily looking into places I might be able to visit, expanding beyond campsites to include day-use hot springs and lodging facilities. This time, I decided to check out something a bit different: a mineral spring inn.

While researching the Chichibu and Yokoze area, I came across an inn where you can use the bath even without staying overnight, and I got curious enough to look into it. The place is called Maruyama Kosen Ryokan.

The Short Version

The inn's specialty seems to be a bath called Kayakuso no Yu, made by boiling medicinal herbs, and it looks like a mineral spring inn you can easily drop into for a day-use bath alone.
As for Rakuten Mobile signal, the official tool didn't return a result, so it came out as unknown.

I've put together the details below.

An Herbal Bath Inn at the Foot of Mount Buko

Maruyama Kosen Ryokan is apparently a mineral spring inn located in Yokoze, Chichibu District, Saitama Prefecture. It seems to sit on the northern foot of Mount Buko, and the official site's logo displays the name in a slightly different order, roughly "Ryokan Maruyama Kosen." The way the name is written may have varied a bit depending on the source or time period.

Check-in seems to be from 3:00 PM and check-out by 10:00 AM as the standard schedule, though the final check-in time apparently varies from around 6:00 PM to 9:00 PM depending on the plan. The rate for one night with two meals runs roughly 11,000 to 14,000 yen per adult (tax and service included), and it seems to change depending on the season, room type, and number of guests. Reservations can apparently be made through the web form on the official site, as well as by phone or through various booking sites.

Komorin

Honestly, I wasn't all that familiar with the term "mineral spring" before this, but it seems to refer to natural water containing minerals and ions, even if it doesn't technically qualify as a hot spring under the Hot Springs Act. Just hearing about an herbal bath makes me want to soak in it slowly at some point.

The Day-Use Bath Kaetsu no Yu and the Rooms

This inn apparently has an attached day-use bath facility called Kaetsu no Yu. On weekdays, admission is 900 yen for adults and 400 yen for children, while on the day before holidays, holidays, and special dates like New Year's, Golden Week, and Obon, it rises to 1,000 yen for adults and 500 yen for children. If you'd like to relax in a private room, there's also apparently a reservable private room available for 2,475 yen for 4 hours. Business hours run from 11:30 AM to 8:00 PM on weekdays (last entry at 7:00 PM), and from 11:30 AM to 2:30 PM on the day before holidays and on holidays (last entry at 2:00 PM), so if you're considering a day trip, it seems worth checking the day of the week first.

Bath types: outdoor bath (one each for men and women), indoor bath/large communal bath (one each for men and women)
Water quality: simple mineral spring water. It's apparently known and loved as Kayakuso no Yu, made by boiling local medicinal herbs
Room types: 12 to 13 rooms total, mostly 7.5-tatami Japanese-style rooms with an attached toilet
Wi-Fi: available
Parking: free, with space for about 30 cars

Dinner apparently centers on the inn's specialty wild boar dishes, including a wild boar hot pot, along with tempura made from local vegetables and wild plants, grilled river fish, rustic hand-pulled udon, and rice cooked with wild plants — a Japanese-style kaiseki course built around seasonal ingredients from the surrounding countryside. Just looking at the photos, you can feel the atmosphere of a mountain village inn.

Rakuten Mobile Signal Conditions

I tried entering this facility's location into the official "My Area Coverage Simulation" tool, but no result was displayed — only some general guidance text showed up. This might be how the tool behaves when address data isn't available for a location, but I couldn't confirm the exact reason.

So I'll mark the overall verdict this time as "unknown." It's not really a good or bad result either way, but if you're planning to actually visit, it might be worth double-checking with your own device and address for peace of mind.

Komorin

As someone who lives by the Rakuten Mobile walking philosophy, this was actually the first time I've come up with an "unknown" result, and it left me feeling a bit frustrated. Precisely because it's tucked away in the mountains, I imagine plenty of people are curious how the signal actually holds up there.

See Rakuten Mobile Details

Checking Out Nearby Attractions

The Yokoze area seems to have a fairly compact cluster of nearby attractions. Terasaka Rice Terraces, about 3 to 5 minutes by car, is apparently also reachable on foot in around 15 minutes. Hitsujiyama Park, known for its moss phlox, is about 5 to 10 minutes by car, and the roadside station Kajuen Ashigakubo is roughly 8 to 10 minutes away. Venture a bit further and you can reach Chichibu Shrine and the roadside station Chichibu in about 10 to 15 minutes, and the Mount Buko trailhead (Ichi no Torii) in about 15 to 20 minutes. Overall, it felt like a location where having a car would make exploring the surrounding area pretty easy.

Wrapping Up

Putting it all together, my impression of Maruyama Kosen Ryokan is that it's a quiet mineral spring inn at the foot of Mount Buko where you can enjoy an herbal bath even on a day trip. The countryside kaiseki course, centered on the wild boar hot pot, is appealing too, and the inn seems well-suited both for an overnight stay and for a day-use bath visit alone.

On the other hand, the Rakuten Mobile signal conditions came out as unknown even with the official tool. If you're concerned about it, you can check with Rakuten Mobile's official tool, so it might be worth taking a look before you actually visit.

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