Hoshino Resorts’ onsen ryokan brand “KAI” will mark its 15th anniversary in 2026. In conjunction with this milestone, the brand will accelerate its expansion toward a total of 30 properties by 2030, while continuing to bring Japan’s unique onsen (hot spring) culture to a modern global audience. In 2026, new openings are planned for KAI Kusatsu (Kusatsu Onsen, Gunma Prefecture), KAI Miyajima (Miyajimaguchi Onsen, Hiroshima Prefecture), and KAI Zao (Zao Onsen, Yamagata Prefecture). In addition, KAI Matsumoto (Asama Onsen, Nagano Prefecture) is scheduled to undergo a full-scale renovation and reopen, followed by KAI’s expansion into Ureshino Onsen in Saga Prefecture in 2027 with the opening of KAI Ureshino.
New Project: “30 Onsen Ryokans, 30 Onsen Cultures”
The Evolution of the KAI Brand
Since its launch in 2011, KAI has continued to explore new possibilities for onsen ryokans while respecting Japan’s traditional onsen culture. Through initiatives such as “Modern Onsen Toji,” the brand has continuously redefined the role of the onsen ryokan. By offering Japanese-inspired spaces designed for contemporary comfort, alongside hospitality that reflects the distinct character of each destination and the beauty of the four seasons, KAI delivers experiences that remain rooted in tradition while embracing a modern sensibility.
Project Background
Marking 15 years of evolution, the new initiative “30 Onsen Ryokans, 30 Onsen Cultures” aims to present the depth of onsen culture—rooted in long-standing Japanese social traditions—as a refined and fulfilling experience for modern travelers. The project embodies the message: 30 onsen destinations across Japan, 30 KAI ryokans, and 30 distinct onsen cultures to celebrate. With its nationwide presence, KAI is uniquely positioned to highlight the cultural diversity of each onsen destination. Looking toward 2030, KAI aims to serve as a bridge between traditions cultivated over generations and the modern world, contributing to the continued vitality and global appreciation of onsen culture.
Note: In anticipation of 30 locations by 2030, information will be released sequentially starting with properties opening by 2026.
What is “Onsen Culture”?
Japan is one of the world’s leading hot spring nations, blessed with abundant geothermal resources. Since ancient times, hot springs have been used in various forms—such as steam baths, sand baths, and therapeutic bathing (toji)—and have become deeply integrated into daily life as a tradition that supports both physical and mental well-being. Onsen have also functioned as centers of local communities, fostering unique cultural identities passed down through generations. Today, the National Council for the Promotion of “Onsen Culture” as a UNESCO Intangible Cultural Heritage defines onsen culture as a social practice rooted in the Japanese way of life—soaking in hot springs to restore both body and mind. Efforts are currently underway to have this culture recognized as a UNESCO Intangible Cultural Heritage.
Phase 1: Enhanced “ABCs of Onsen Culture” Across All Properties
The educational program “ABCs of Hot Springs,” previously offered at all KAI properties, will be evolved into “ABCs of Onsen Culture.” Building on the knowledge cultivated through modern onsen healing practices, the program will deepen into an experience that conveys the cultural traditions of wellness rooted in each region. Designed as an accessible introduction to local onsen culture, it offers experiences that are both approachable and enriching. At KAI Beppu, in Japan’s leading hot spring destination, guests can learn about its skin-beautifying waters and create an onsen mist as a finishing touch to their bathhouse-hopping experience. At KAI Unzen, located near Unzen Jigoku—a geothermal area known for its dramatic steam vents and volcanic activity—guests can learn about the long history of coexistence between local people and this powerful natural landscape. They can also observe the traditional “kantsuke” (sake warming) system, which uses natural high-temperature steam, offering a firsthand experience of the area’s geothermal energy.
“ABCs of Onsen Culture” Overview
■ Period: June 1, 2026 – year-round
■ Price: Free of charge *Some experiences may require a fee
■ Reservation: Not required *Some experiences may require advance reservation
New Information on Four Properties Opening Sequentially Through 2026
[KAI Kusatsu] Opening June 7, 2026 — A New Retreat Bridging the Lively Hot Spring Town and a Serene Ryokan through a Private Tunnel
KAI Kusatsu introduces a new style of stay that seamlessly connects the vibrant hot spring town with a tranquil ryokan setting via a private tunnel. Guest rooms feature the locally inspired “Silk Art Rooms,” reflecting Gunma’s rich heritage as a center of silk and textile production. The property’s large onsen baths offer two types of highly acidic hot spring waters, characteristic of Kusatsu’s renowned springs. From its opening, KAI Kusatsu will also present the “ABCs of Onsen Culture,” an original program designed to deepen guests’ understanding of the area’s abundant thermal waters, the historical evolution of the town since the Edo period, and more enriching ways to experience the hot spring district.
Press release available here: https://hoshinoresorts.com/en/presscenter/10/2025/191245/
[KAI Miyajima] Opening July 23, 2026 — Discover the Evolving Charms of Hiroshima through All Ocean-View Rooms and Creative Kaiseki Cuisine
KAI Miyajima features all ocean-view guest rooms, including the signature “Umigiri (Sea Mist) Rooms” inspired by the ethereal sea mist that symbolizes the Setouchi region. Guests can enjoy kaiseki cuisine that highlights the rich food culture of Hiroshima and the Setouchi area, presented with a refined sense of creativity and thoughtful interpretation. The property also revives the traditional “Setouchi Ancient Sauna,” offering a modern reinterpretation of a bathing culture that dates back to the Kamakura period and was once deeply rooted in local daily life. Reimagined for contemporary comfort, this experience invites guests to immerse themselves in the region’s history and cultural heritage.
Press release available here: https://hoshinoresorts.com/en/news/08/2025/182531/
[KAI Matsumoto] Reopening August 4, 2026 — The First KAI Property to Introduce Italian Dining, Offering a “Matsumoto Elegante” Stay Immersed in Music, Wine, and Hot Spring Serenity
KAI Matsumoto is located in Matsumoto City, renowned as a center of art and culture. The property features eight types of onsen baths and five saunas, offering a richly varied bathing experience. Each guest room is equipped with a record player, allowing guests to immerse themselves in music within the privacy of their own space. For dinner, KAI Matsumoto introduces its first-ever Italian-inspired cuisine, thoughtfully paired with NAGANO WINE and music-inspired culinary expressions. After dinner, guests are invited to enjoy a lobby concert while savoring a glass of wine, creating a refined and memorable conclusion to their stay.
Press release available here: https://hoshinoresorts.com/en/news/04/2026/207251/
[KAI Zao] Opening October 15, 2026 — A Spiral Journey to Wellness Experience Centered on Onsen, Sauna, and an Observatory Lounge
KAI Zao is set within the dramatic natural landscape of the Zao mountain range. A defining feature of the property is its 360-degree panoramic rooftop terrace, inspired by “Okama,” the iconic crater lake of Zao. Guests are invited to embark on an immersive wellness journey that unfolds in a circular sequence of experiences—from highly acidic hot spring baths and sauna sessions to indoor cooling and relaxation spaces—culminating in a sky jacuzzi, reached on foot as the final destination of this curated flow. This unique experience encourages guests to move seamlessly through each stage while taking in the surrounding natural beauty. Drawing on the powerful energy of the region and the restorative qualities of its hot springs, KAI Zao offers a stay designed to foster a deeper connection with onsen culture and inspire a profound sense of renewal.
Press release available here: https://hoshinoresorts.com/en/news/04/2026/207703/
New Initiative & Latest News
KAI Ureshino, scheduled to open in the summer of 2027, will mark KAI’s first entry into Saga Prefecture. The property will offer a stay that fully embraces the distinctive appeal of Ureshino Onsen, widely renowned as one of Japan’s three most celebrated “skin-beautifying” hot springs.
About KAI Brand
Onsen Ryokan loved by local and overseas travelers
KAI is a leading brand of onsen ryokan where every establishment offers a contemporary take on traditional Japanese inn whilst keeping Western comforts. KAI invites one to discover the multifaceted aspects of Japan through natural hot springs, exploration of local arts and entertainment, and classic Kaiseki-style course meals using local and seasonal flavors. Experience Washoku, Japanese cuisine, presented on carefully selected ceramics for full exposure to culinary sensations.
About Hoshino Resorts
Hoshino Resorts was first established as a Japanese inn/ryokan in 1914 in Karuizawa in Nagano Prefecture before it began the operation of other resorts in Japan. Today, it has evolved into a highly influential hotel management company and is run by 4th-generation family member Yoshiharu Hoshino. Providing a unique experience focused on the local charms of each destination and a high level of omotenashi, Japanese-style hospitality, the company has expanded rapidly out of Karuizawa since 2001 and now operates more than 65 accommodations both in and outside Japan with one of the following categories: luxury hotel brand "HOSHINOYA," hot spring ryokan brand "KAI," countryside resort hotel brand "RISONARE," city tourism hotel brand "OMO," free-spirited hotel brand "BEB," mountain hotel brand "LUCY" or other unique lodgings.
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