Discover Kusatsu Onsen: Five Japanese Bath and Skincare Treasures

In autumn, Kusatsu Onsen welcomes visitors with crimson leaves, cool mountain air, and clouds of steam rising from its famous Yubatake. Nestled in Gunma Prefecture, this celebrated hot spring town offers a beautiful setting for slowing down and enjoying Japan’s bathing culture.

For October’s Onsen Box, we have selected five bath and skincare products from Kusatsu Onsen’s Yunoka Honpo. From a moisturizing sheet mask to bath powders and a citrus-scented hand cream, each brings a different part of this hot spring town into your everyday routine.

What Makes Kusatsu’s Hot Spring Water Special?

Kusatsu is recognized as one of Japan’s three famous hot springs. Its natural springs produce more than 32,300 liters of water per minute, supporting the town’s tradition of bathing in freshly flowing spring water. The Yubatake source has a pH of approximately 2.1, making it strongly acidic. At the Yubatake, steaming water passes through seven wooden channels, cooling in the open air before being used for bathing.

Kusatsu has long been associated with toji, Japan’s tradition of staying at hot springs for rest and recuperation. The Japan Spa Association lists fatigue recovery, cold sensitivity, and chronic muscle or joint discomfort among the bathing indications associated with its springs. Acidic spring water also has cleansing properties.

These characteristics belong to the natural springs themselves. The products below offer their own cosmetic and sensory benefits; they do not reproduce the full composition or therapeutic effects of bathing in Kusatsu’s natural waters.

1. Kusatsu Onsen Mask: Multi-Moist

A Moisturizing Moment with Genuine Kusatsu Spring Water

After a busy day, a sheet mask offers a simple reason to pause. This Japanese-made mask contains genuine Kusatsu hot spring water sourced from Yamamotokan’s Waka-no-Yu spring.

Its essence combines hot spring water with collagen, placenta extract, arbutin, and hyaluronic acid. Alongside moisturizing ingredients such as glycerin and trehalose, the formula is designed to leave skin feeling hydrated, soft, and supple.

Each sheet contains 15 ml of essence. Your October Onsen Box includes one individually packaged mask, ready for an evening of personal care.

How to use: After cleansing, unfold the mask and align it with your eyes and mouth. Leave it on for approximately 10 minutes, then remove it and gently press the remaining essence into your skin.

The maker notes that a characteristic Kusatsu scent may occasionally be noticeable and does not indicate a quality problem.

2. Kusatsu Bath Powder

A Bath with Kusatsu’s “Hot Spring Flowers”

This bath powder contains yunohana collected in Kusatsu, Gunma. Often translated as “hot spring flowers,” yunohana refers to mineral deposits associated with hot spring water.

In this formula, the yunohana appears on the ingredient list as mineral salts, identified by the maker as a moisturizing ingredient. The powder also contains sodium sulfate, sodium chloride, calcium carbonate, and titanium dioxide.

Its appeal lies in that connection to Kusatsu: a locally sourced hot spring ingredient incorporated into a convenient home-bathing product. Add it to a warm bath and make time for yourself on a cool autumn evening.

Contents: One 25 g sachet for one bath.

How to use: Dissolve the entire sachet in 150–200 liters of warm bathwater and stir thoroughly. Small white particles may remain at the bottom; the maker states that this is normal. Rinse them away when draining.

Do not use in an enamel bathtub or reuse the bathwater for laundry. Drain promptly after use.

3. Kusatsu Bath Powder: Sulfur Scent

The Characteristic Aroma of an Onsen Town

For many visitors, the sulfur scent around Kusatsu’s springs is an unforgettable part of the experience. This bath powder recreates that aromatic atmosphere, turning the water a milky white for an inviting onsen-style soak at home.

While the previous powder highlights Kusatsu-sourced yunohana, this version emphasizes the town’s characteristic sulfur aroma. Its formula includes mineral salts, sodium sulfate, calcium carbonate, and titanium dioxide.

The cloudy water and distinctive scent offer a different bathing experience—ideal for an evening when you want to recall the steam and atmosphere of a Japanese hot spring town.

Contents: One 25 g sachet for one bath.

How to use: Dissolve one sachet in 150–200 liters of warm water and stir well. Small dark particles may remain; the maker explains that these come from components in the salts and are not a quality issue.

Do not use in an enamel bathtub or reuse the water for laundry. Drain promptly and rinse away any residue.

4. Kusatsu Carbonated Bath Tablet

Gentle Effervescence for Your Bath Ritual

Drop this tablet into warm water and watch it fizz as it dissolves. It creates a pale, milky green bath, adding a refreshing visual touch to your evening routine.

The Japanese-made tablet contains genuine Kusatsu hot spring water from Yamamotokan’s Waka-no-Yu spring, included as a moisturizing ingredient. Its formula also contains succinic acid, sodium bicarbonate, and sodium carbonate.

For those who enjoy watching a bath tablet dissolve, it offers a pleasant alternative to the two powders. The maker states that it contains no sulfur of the type that can damage bathtubs or bath heaters.

Contents: One 30 g tablet for one bath.

How to use: Add the tablet to approximately 200 liters of warm water and dissolve thoroughly before bathing. Use immediately after opening.

Avoid use in artificial-marble bathtubs and continuously circulating “24-hour” bath systems. The bathtub may become slippery, so take care when entering and leaving

5. Kusatsu Onsen Hand Cream

Spring Water and a Refreshing Kabosu Scent

Bring a small reminder of Kusatsu into your daily routine with this compact hand cream. Its kabosu fragrance adds a refreshing Japanese citrus note, while the maker describes the finish as moisturized and smooth.

The formula contains hot spring water from Yamamotokan’s Waka-no-Yu spring, alongside glycerin, mineral oil, a hyaluronic-acid derivative, and three types of ceramides: NP, AP, and EOP. These ingredients complement a hand-care formula designed to help keep skin feeling comfortable and moisturized.

The 15 g jar is convenient for a handbag, travel pouch, or desk drawer. Use it after washing your hands or whenever you want a small moment of care during the day.

How to use: Apply an appropriate amount to your hands and massage until well absorbed. Stop using it if irritation occurs.

Create Your Own Kusatsu-Inspired Evening

Choose one of the three bath products for your soak, enjoy the face mask afterward, and finish with a little hand cream. Each product brings a different texture, scent, or ritual to the experience.

This October’s Onsen Box invites you to discover Kusatsu through locally selected bath and skincare treasures—a little connection to Japan’s hot spring culture, wherever you call home.

More Kusatsu Onsen Info: https://onsenbox.jp/season-kusatsu/

Always follow each product’s packaging instructions and check compatibility with your bathtub. Discontinue use if irritation occurs.