KAI Zao opens on 15 October 2026 in Zao Onsen, Yamagata Prefecture, bringing 49 rooms and a whole lot of soaking to one of Japan’s oldest hot spring towns.
Zao Onsen has been bubbling away for more than 1,900 years, with highly acidic sulphur springs fed by the volcanic landscape surrounding the Zao Mountain Range. KAI Zao plans to put those waters to work with three baths containing different mineral concentrations, alongside saunas and relaxation spaces.
The idea is to work your way around the property on what KAI calls a ‘spiral journey’ of hot springs, sauna sessions, cooling off and generally doing very little. Eventually, you’ll reach the rooftop terrace and its sky jacuzzi, where 360-degree views stretch from the Zao Mountain Range to the Asahi Mountains.
The circular design takes its cues from nearby Okama, the volcanic crater lake that has become one of the region’s best-known landmarks.
They haven’t forgotten about dinner, either. The local spin continues with a kaiseki menu featuring Yamagata ingredients, including mountain vegetables, mushrooms, duck and mokuzu crab, with the main event being Gassan Nabe, a steaming hot pot named after one of the prefecture’s sacred mountains.
It’s all part of KAI’s attempt to reposition Zao as a destination worth visiting beyond ski season. Frankly, sitting in a rooftop jacuzzi staring at the mountains sounds like a pretty solid argument to us.
Why It Exists
To give you a very good reason to visit Zao when there isn’t a ski boot in sight.
The Vibe
Ancient onsen town meets modern mountain retreat, with volcanic baths, saunas and a rooftop jacuzzi doing most of the convincing.
Your Bed Tonight
One of 49 rooms designed for doing very little between soaks, preferably while wrapped in something fluffy.
The Thing You’ll Brag About Later
Working your way through three mineral-rich baths before ending up in a rooftop jacuzzi with 360-degree views of the Zao and Asahi mountains.
Eat / Drink This
Go for the Gassan Nabe, a steaming hot pot loaded with Yamagata flavours and named after one of the prefecture’s sacred mountains.
Steal This Local Move
Follow KAI Zao’s ‘spiral journey’: soak, sauna, cool down, repeat.
Share >
More Stays
Treehouses have come a bloody long way since Dad nailed three planks of timber to a gum tree and told you not to fall out.
There’s a new Golden Route in Japan - it's greener than the other, and it’s probably not where you thought it was.
Why this so-called “airport town” is secretly a crash course in Japan, even if you’ve only got a few hours.
