Awanoyu (Shirahone Onsen)

Which Awanoyu this is

Awanoyu (泡の湯, “bubble bath”) is a name used by more than one inn in Japan. This page covers Awanoyu at Shirahone Onsen, 4181 Azumi, Matsumoto, in Nagano Prefecture, the inn famous for its milky mixed outdoor bath. A different inn, Awanoyu Onsen Miyoshiso in Kodamagawa, Yamagata Prefecture, announced it would close at the end of December 2019, so if you see older references to an Awanoyu in Yamagata, that one is gone. For the village as a whole, see Shirahone Onsen.

What to expect

Shirahone is a small hot spring village in a steep, forested valley on the road between Matsumoto and Norikura. The inn’s signature is a large mixed outdoor bath (konyoku) of milky, pale blue-white water, about 70 tsubo (roughly 230 square metres), with a stream of hot water falling from a spout several metres above the surface. Rocks in the middle and planting around the edges break up the view.

The water is unusual. The inn’s analysis lists a sulphur-bearing calcium-magnesium bicarbonate spring (hydrogen sulphide type), pH 6.3, flowing at 1,730 litres a minute, which the inn says is one of the largest flows in Nagano. It comes out of the ground clear at about 99°F37.3°C and turns milky cream or even bluish as it meets the air. Because it is so rich in carbon dioxide, fine bubbles gather on your skin, which is where the name comes from. The inn keeps the main baths lukewarm, roughly 99-104°F37 to 40°C, changing with the outside temperature; heating it more, it says, would drive the gas off. Expect a long, gentle soak rather than a hot one. Some baths are partly heated.

Besides the mixed bath there are separate men’s and women’s indoor baths (one lukewarm at about 99°F37°C, one at about 104°F40°C) and separate outdoor baths, so nobody has to use the mixed bath. The source is drinkable, and breakfast includes the inn’s hot spring rice porridge.

Getting there

By car: Prefectural Road 300, the Shirahone Onsen road, was widened and opened for year-round use on December 1, 2012. The inn says it freezes in winter, so come with winter tyres and chains. From Tokyo, the Chuo and Nagano expressways take about 2 hours 30 minutes to the Matsumoto IC, then allow about 60 minutes to the inn. From the Gifu side, Hirayu Onsen is about 20 minutes away.

By bus: in the 2026 season (April 17 to November 15), Alpico buses run from Shin-Shimashima, the terminus of the Kamikochi Line railway from Matsumoto, with a change at the Sawando bus terminal for Shirahone Onsen and the Awanoyu-mae stop. There are only a few buses a day, so check the timetable on the inn’s access page against the 10:30 to 13:30 day-bathing window. The Nohi bus from Takayama via Hirayu connects at Sawando and has been reservation-only since April 1, 2024. Outside the bus season you need a car or a taxi from Shin-Shimashima or Matsumoto.

When to go

Shirahone is a mountain village, and the seasons feel strong here. Autumn colour brings the biggest crowds. Winter brings snow around the outdoor bath, but the road freezes and the inn may close day bathing in bad weather. Spring and summer are green and quieter, and the lukewarm water is comfortable even on warm days.

For day bathing, arrive close to 10:30 on a weekday. The inn may limit entry when it is crowded or close the desk early.

Prices and booking

• Day bathing: ¥1,000 for junior high and up, ¥600 for ages 3 to 12, 10:30 to 13:30 (leave by 14:00). This covers the mixed outdoor bath and the separate indoor and outdoor baths.
• Extras: towel ¥200, bath towel ¥800, shower cap ¥100, razor ¥200, all including tax.
• Open days: the inn posts a day-bathing calendar on its website. Closed days change, and it can also close for maintenance or in winter weather. In 2026 it warned that boiler fuel supplies were unstable because of tension in the Middle East and that it might close at short notice, so phone on the day (0263-93-2101).
• Overnight stays: book through the inn’s website or by phone. Guests can use the baths through the night, except during cleaning from 10:00 to 10:30 and 14:00 to 15:00.

Overnight guests also pay the Matsumoto accommodation tax, introduced on June 1, 2026: ¥200 per person per night until May 31, 2029 (then ¥300), when the room-only rate is ¥6,000 or more before tax.

Onsen etiquette

Bathing is naked. Swimsuits are not allowed in the mixed bath, but you may wrap yourself in a bath towel. Overnight guests get thick bath towels at the outdoor bath changing room and can borrow bathing wraps (yuami-gi) free; day visitors get neither and must bring their own bath towel or buy one. Wash before you get in, keep your movement low and slow (the water is deep enough to move around half-crouched), and do not stare or take photos. The separate-sex baths follow normal onsen rules. Remove gold, silver and platinum jewellery, since the minerals can discolour it.

Children are welcome and pay a reduced day rate; families who prefer can use the separate men’s and women’s baths.

Where to stay nearby

Staying at Awanoyu itself gives you the baths at night and early morning, when they are quietest. Shirahone has several other ryokan, many of which offer day bathing. Norikura Kogen is higher up the valley, and Kamikochi is reachable by bus via Sawando in season. Asama Onsen and central Matsumoto are the lowland bases.

Safety notes

• Winter roads: the access road freezes. Do not attempt it without winter tyres, and carry chains.
• Long soaks: the water feels mild, so it is easy to stay in for a long time. Drink water and get out if you feel lightheaded.
• Footing: rock edges and steps into the outdoor bath are slippery.
• Remote location: services are limited in the village. Check bus times before you go, as there are only a few departures.

Nearby stops worth adding

Kamikochi, the alpine valley below the Hotaka peaks, is the big draw nearby and closes for the season from mid-November to mid-April. Norikura Kogen has waterfalls and hiking. Back in the valley, Shirahone Onsen has other inns to compare its milky water with.