Five Japanese Bath Additives to Refresh Your Summer

Why Japanese People Still Love a Hot Bath in the Heat

Summer in Japan is intense.

Temperatures can climb close to 40°C (104°F), with high humidity making the heat feel even more exhausting. Yet even in the middle of summer, many Japanese people still enjoy soaking in a bathtub.

It may sound surprising: Why take a warm bath when it is already so hot outside?

For me, it is one of my favorite summer rituals.

After spending the day moving between intense outdoor heat and heavily air-conditioned rooms, I like to soak in a hot bath and let myself warm up and sweat. That wonderfully fresh feeling when I step out of the bath is one of my favorite parts of a Japanese summer.

Rather than thinking of bathing simply as a way to wash the body, in Japan we often treat the bath as a place to reset — physically and mentally.

For this month’s Onsen Box, we have selected five very different Japanese bath additives that are especially fun to experience during summer.

Some cool you down with Japanese mint. Some encourage a warming sweat. Others surround you with the refreshing scent of Japanese forests.

Here are our five summer picks.

1. Hakka-yu — Japanese Mint Bath from Hokkaido

If there is one fragrance that instantly says “Japanese summer,” it may be hakka.

Hakka is Japanese mint, and this bath additive from Kitami, Hokkaido contains Japanese mint grown on the maker’s own partner farm. One single-use 30g packet transforms approximately 200 liters of bathwater into a refreshing mint-green cloudy bath. Its formula includes peppermint oil and Mentha arvensis leaf extract.

The moment you open the packet, the clean, nostalgic aroma of Japanese mint emerges.

Why we love it in summer

The contrast is wonderful: warm bathwater combined with the fresh sensation and aroma of mint.

You can enjoy the relaxing warmth of a Japanese bath without the experience feeling heavy or overly rich for a summer evening.

For anyone experiencing Japanese summer wellness for the first time, this is our essential August bath.

2. Germa Bath — The Sweating Bath

This one takes the opposite approach.

Instead of trying to make your bath feel cooler, Germa Bath is all about getting seriously warm and sweaty.

The Japanese bath salt combines mineral salts with germanium and chili pepper extract. The formula is designed to create a strongly warming bathing experience, and it has become particularly known in Japan as a “sweating bath.”

Why use a warming bath in summer?

It sounds contradictory — and that’s exactly what makes it interesting.

Japanese summers often mean moving repeatedly between extremely hot streets and aggressively air-conditioned trains, offices, shops, and hotel rooms.

Sometimes what feels best at the end of that day isn’t another blast of cold air. It’s a proper soak, a good sweat, and that wonderfully clean, refreshed feeling afterwards.

Think of Germa Bath as our “sweat it out” summer bath.

3. Yakuto Hiba — Japanese Forest Bath

Next, we leave mint and minerals behind and head into the forest.

Hiba is a Japanese conifer famous for its distinctive woody fragrance, particularly associated with northern Japan.

Yakuto Hiba is a Japanese medicinal-style bath additive that brings this characteristic forest aroma into the bathtub.

Why we chose it for summer

In Japanese culture, “coolness” isn’t always about temperature.

Sometimes it is psychological.

The sound of a wind chime, the shade beneath a tree, flowing water, a bamboo garden — these things make us feel cooler.

Hiba works in much the same way.

Its clean woody aroma evokes a quiet Japanese forest, making it particularly lovely after a hot, busy summer day.

4. Matsu no Sei — A Classic Japanese Pine Bath

There is something wonderfully nostalgic about Matsu no Sei.

Its roots go back to the early Showa era, making it a long-selling Japanese medicinal bath product. Its forest-inspired fragrance originated from a German pine-bath tradition, while the modern formulation incorporates Japanese botanical ingredients including Japanese angelica root (toki) and bitter orange peel (tohi) extracts.

Why we chose it for summer

Imagine escaping the city heat and entering a cool mountain forest.

That’s the feeling we wanted from this selection.

While Hakka-yu gives you a crisp mint experience, Matsu no Sei approaches summer wellness through forest bathing — shinrin-yoku — and nostalgic herbal aromas.

It is a different kind of refreshment: quiet, green and deeply Japanese.

5. Shirokuma no Kimochi — Ice-Cool Bath Salt

And finally, the most obviously summery member of our collection.

Even the name is fun:

Shirokuma no Kimochi — “The Polar Bear’s Feeling.”

This cooling bath salt was created specifically to make bath time more enjoyable during hot weather.

After the warming and forest-inspired baths above, this is the playful cool-down experience of our August collection.

Why we chose it for summer

Because sometimes you simply want to feel cool!

It combines the ritual of soaking in a Japanese bathtub with a refreshing cooling sensation — an ideal introduction for anyone who finds the idea of taking a bath during a 35°C summer slightly crazy.

Try it after a long, humid day and discover why a summer bath can be surprisingly refreshing.

♨️Two Ways Japan Approaches the Summer Bath

What makes these five products interesting is that they reveal two completely different Japanese approaches to summer bathing.

One is to cool the senses — using mint, refreshing fragrances and cooling ingredients.

The other is almost the opposite:

Get warm. Sweat. Then refresh.

That’s why this month’s selection ranges from the crisp sensation of Hakka-yu and Shirokuma no Kimochi to the warming Germa Bath and the forest-inspired aromas of Hiba and Matsu no Sei.

There isn’t just one “correct” Japanese summer bath.

Choose the experience that matches your mood.