Yunohana: Real Hot-Spring Crystals for Your Bath at Home

Most “onsen at home” products are perfume and colouring. This one is not.

Yunohana (湯の花) is the mineral crust that hot-spring steam leaves behind — and at Beppu, in Oita, it is still farmed the old way, in low thatched huts built over the volcanic vents. A sachet of it turns an ordinary bathtub milky, sulphurous, and unmistakably like a Japanese hot spring.

It is also flat, light, and unbreakable, which makes it a very sensible thing to carry home. But it comes with real conditions, and I would rather set those out properly than sell you something that damages your bathroom.

What It Actually Is

At Myōban Onsen, on the hillside above Beppu, steam rises continuously from the ground. Farmers there learned, some three hundred years ago, to build huts over the vents, lay a floor of special clay inside, and let the steam pass slowly up through it. Over weeks, the minerals in the steam crystallise on the surface — and that crust is scraped off by hand.

Nothing is manufactured. The steam does the work; the people simply make a place for it to happen.

In March 2006, Japan designated this production method an Important Intangible Folk Cultural Property (重要無形民俗文化財) — the same category of protection given to traditional festivals and crafts. There are not many bath products in the world with that on the label.

The crystals are largely aluminium and magnesium sulphates with iron compounds. In Japan the product is sold as a quasi-drug (医薬部外品) with the traditional indications you would expect of a hot spring — stiffness, poor circulation, aching joints. I would treat that as tradition rather than medicine, but the minerals themselves are entirely genuine.

Please Read This Before You Buy

This is the part that matters, and most listings bury it. The maker’s own guidance:

• Baths with a reheating function (oidaki) — the maker says this is not recommended. Their instruction is to fill the tub with freshly heated water and not run the reheating cycle. In a reheat system the bathwater is pumped back through the boiler, and these minerals are not kind to it.
• Circulating baths — the maker warns that problems can develop over years of use, and that regular cleaning and maintenance is necessary. If your bath recirculates its water, think carefully.
• Jacuzzi and 24-hour bath systems — the maker does not address these specifically, but the same logic applies: if water passes through pumps, jets or filters, this is not the product for it. I would not use it.
• It will stain the tub. There is sulphur and iron in it. The maker publishes a removal method involving bleach and paper towels, which tells you what you need to know. Drain the bath soon after use and rinse the tub.
• It smells. Properly. Of sulphur and a little of iron. That is the point, but a household should be warned.

In short: a plain, non-circulating bathtub is what this is for. If that is your bathroom, it is wonderful. If it is not, please buy something else — a scented tablet will not damage anything, and this will.

Where to Buy

The one I would point you to is the Murakami Shōkai official product — the Myōban maker itself, in a box of 15 sachets. One sachet does one normal bathtub.

How to Have It Delivered to Your Tokyo Hotel

Amazon Japan and Rakuten can both deliver to the hotel where you are staying.

1. Enter the hotel’s address in the delivery field, with your own name and room number (for example, “Smith / Room 812”).
2. Ask the hotel first. Most will hold a parcel for a guest; not all will.
3. On Amazon.co.jp the language switch is at the top right of the screen. Rakuten is Japanese-only, so your browser’s translation feature is the easy way through.

Fifteen paper sachets weigh very little and lie flat in a case, so this is one of the easier souvenirs to bring home.

If You Are Visiting an Onsen Town

Yunohana is from Beppu, in Kyushu — a long way from Tokyo. If your onsen day trip is closer to the capital, Kusatsu Onsen is reachable by direct bus from Shinjuku, and has its own famously fierce, acidic water. The two are quite different hot springs; this is simply the one you can take home in a suitcase.

Who Is This For?

Anyone who came to Japan, sank into a hot spring, and thought: I would like this again, at home. Provided your bathtub is a simple one, this gets closer than anything else on a shop shelf — because it is not an imitation of a hot spring. It is a hot spring, dried.

Note: Please follow the maker’s instructions on the packet, and check with your landlord or building if you are unsure about your bath system. Prices and availability change.

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