Authentic Nakanosawa Onsen offers nature, samurai, serenity

Nakanosawa Onsen is a peaceful little town in the mountain heartland of Aizu surrounded by the mountains and lakes of Bandai Asahi National Park. Many historic sites from the Samurai era are also nearby, most famously Tsurago-jo castle and there are plenty of inter-active experiences for all ages to discover more about them on offer.

Soaking in the hot stream at Nakanosawa Onsen's source on Mt Adatara
The most amazing hot bath you will ever take – in the hot (very!) stream source of Nakanosawa Onsen high on Mount Adatara © Shinji-san

Set between Mt Adatara and Mt Bandai, Nakanosawa’s onsen are reckoned among the best in Japan for water quality and purity thanks to the massive volume of hot spring water.

The source of the onsen was discovered 380 years ago at 1250m above sea level. With a flow of 13,400 litres per minute, according to research done by the Aizu Insurance Office, it is the most powerful in Japan.

The source springs up from the Adatara Mountains. In 1818, local people drew hot water from the deep source, and it gradually became the current hot spring town.

“This is the most amazing onsen I have ever tried” says Japanezy’s Owain Price, who hiked up through deep snow to reach it recently with local Ryokan owner Shinji-san.

Fluorescent mud at the source of Nakanosawa Onsen on Mt Adatara
Fluorescent mud in the source stream – looks weird, but takes all your aches and pains away says Jsummer’s onsen tester © Shinji-san

“The hike follows a canyon wall along a narrow track where the villagers have laid their pipe channeling the super hot water down to the village below. The river’s flow is amazing – it cascades through a cave then drops over a 50m fall which creates what could be the World’s highest natural hot shower!”

“The water is super hot – even on a snowy winter’s day with a chill wind howling I had to ease myself into it. After getting my feet wet first I found a slightly cooler pool to one side to immerse myself in. After a short soak I hopped out and found all my aches and pains from the hike up had miraculously dissapeared. No wonder the locals claim it as one of the most therapeutic onsens in Japan.”

The water colour varies day to day from clear to milky, with a PH level between 1.7 – 2.1 that’s renowned for its therapeutic properties.

Forest hike at Nakanosawa Onsen
Shinto spirits live in nature and it’s hard not to agree strolling the forest

You can hike up the side of the river valley and just sit in the hot stream, which is much easier in summer than our winter experience. It can easily be done as a guided trip – check our feature on that here.

Nakanosawa open air ryokan onsen
No need to hike further than your Ryokan’s onsen .. several have amazing in-room private onsens too! © Carmen Price

But most people will be more than happy just enjoying the numerous beautiful onsen on offer in the cluster of ryokans and small hotels in and around Nakanosawa Onsen village that are all served by this bountiful spring.

Waterfall in Bandai Asahi National Park, Nakanoswa Onsen
Discover the beauty of Bandai Asahi National Park from Nakanoswa Onsen

These offer excellent value and traditional hospitality, and usually exceptional local cuisine based on fresh seasonal ingredients.

Sure, this is not the only area in Japan to claim the best rice and best sake, based on the essential ingredient of pure mountain water for those, but it’s hard to argue with the claims putting them to the taste test locally.

the source of Nakanosawa Onsen thermal water
It’s easier to hike up to and bathe in the hot river in summer. For centuries villagers have channeled the waters to Nakanosawa

Nakanosawa Onsen sights and activities

This part of Aizu is also the historical setting for the real “Last Samurai” war – the Boshin War – and its final battles. Many of the Aizu supporters of the defeated samurai were exiled to the northern tip of Honshu after the war, and the area endured years of hardship.

There are many fascinating sites relating to the Samurai era, most famously and grandly the restored Tsurago-jo (castle) outside Aizu-Wakamatsu city.

There are also some great participatory activities to get into the samurai spirit everyone in the family will love. Some great tours are available to take advantage of these, for example:

Tsurago-jo Castle at night
Tsuraga-jo Castle at night – the rebuilt castle is a famous “Last Samurai” site

The Aizu Samurai Spirit Grand Tour Tsuruga Castle in Aizu Wakamatsu city is a favourite. It’s a bit over an hour’s drive away. A tour to get the most out of it is the Aizu Samurai Spirit Grand Tour, which is available for 2 – 8 participants for ¥33000 per person, includes transport from Aizuwakamatsu Station.

  • Learn the history of the last samurai in Japan.
  • Learn the history at Tsuruga Castle and overlook the Aizu area from the castle tower.
  • You will experience Kyudo at the Samurai Nisshin School.
  • Visiting with commentary by a veteran guide.
Nisshinkan Samurai School display
Nisshinkan Samurai School display – enjoy fascinating displays and fun participatory activities © Carmen Price

The Aizu Samurai Education Experience is another option, good for families. Visit what was once the Nisshinkan school where Samurai children attended, learning history, martial arts, manners, astronomy and much more besides.

The displays are fascinating and there are fun participatory activities for all ages ranging from Kyudo – Japanese archery – to painting to Zazen meditation.

Available for 2 – 8 participants for ¥30000 per person, includes transport from Aizuwakamatsu Station.

lake fishing in Aizu near Nakanosawa Onsen
Lake fishing is fun for all ages

Lake / Ice fishing for little smelt is popular and easy to try on nearby lakes like Lake Akimoto. Catch and cook is the way to go – the huts have cookers to do just that. In winter they are stuck in ice, so you simply ice fish from inside through holes cut in the ice.

In other seasons you fish from the floating huts.

Snowshoeing is a more active way to get outdoors in winter. Morning and afternoon tours run from the Urubandai Kogen Hotel Lobby from ¥5000 per person past beautiful beech forest and lakes. You can see marks of bears and may sight antelope.

Snowshoeing at Nakanosawa Onsen, Aizu
Snowshoe adventure in the forest

All these tours can be booked and more info had from

Snow monkeys can often be see driving in the Bandai National Park on the roads up to Nekoma and Grandeco ski areas. Bears still live in the mountains too.

Nakanosawa Onsen autumn views
The Nakanosawa Onsen area is beautiful in all seasons

Onsen and Forest Therapy is very popular in Japan. With 35 million people living in the greater metropolitan area it’s no surprise escaping to pure nature is popular, and the forests, waterfalls and hot river around Nakoanosawa are pretty special for this.

How do you get to Nakanosawa Onsen? 

By train is quickest way to Nakanosawa Onsen from Tokyo. Take the Tohoku shinkansen to Koriyama, then the local Banetsu Line to Inawashiro.

You can use a JR East Tohoku Rail Pass to visit the area then continue further north as detailed in our JR Pass itinerary ideas feature.

An Express Aizu Bus service runs from Haneda and Tokyo Station.

From Haneda Airport (International Terminal) Take Highway Bus (Aizu Bus) at Bus Stop No. 6 and get off at Inawashiro Station.

From Tokyo Station: Take Highway Bus (Aizu Bus) at Kajibashi parking.

Self driving take the Inawashiro Bandai Kogen IC off the Banetsu Expressway, 15km to Nakanosawa Onsen and just under 3km more to Numajiri Ski Resort.

NB: for Nakanosawa Onsen accommodation & restaurant options check our guide to those here

The Aizu Bus at Stop 6, Haneda Airport
Catch the Aizu Bus direct from Haneda International Terminal Stop Number 6