Image: An illustration depicting KAI Kusatsu, connected by a tunnel to the Kusatsu Onsen townscape in the foreground and nestled on a hill in the background.
Hoshino Resorts' hot spring ryokan brand "KAI" has decided to open its 24th property in Kusatsu Onsen, Gunma Prefecture. The facility will be named KAI Kusatsu, and its opening is scheduled for the spring of 2026. This will be the first KAI brand property in Gunma Prefecture and the second property for Hoshino Resorts in the area. The concept is "A forest hot spring inn and onsen town connected by a tunnel." Located on a hill overlooking Mt. Kusatsu-Shirane, the expansive and nature-rich grounds will house multiple buildings, including guest room wings, a bathhouse building, and a lounge building. It will feature a private tunnel exclusively for guests, providing access to the Kusatsu Onsen town. This will offer a stay where guests can enjoy the contrasting atmospheres of KAI Kusatsu, surrounded by nature, and the historic and vibrant Kusatsu Onsen town.
About KAI Kusatsu
KAI Kusatsu is a new property situated on a hill with views of Mt. Kusatsu-Shirane, a well-known symbol of the Kusatsu area. The concept aims to blend the tranquility of a nature-rich retreat with the vibrant atmosphere of the local hot spring town. The hotel grounds are extensive and feature a courtyard and several buildings. A key feature is a private passage for guests that provides easy access to the Kusatsu Onsen town. This unique connection allows guests to experience both the peaceful, natural surroundings of KAI Kusatsu and the lively, historical streets of the onsen town. The goal is to offer a stay where guests can appreciate the diverse attractions of the Kusatsu region through these two distinct environments.
About Kusatsu Onsen
Kusatsu Onsen is one of Japan's three most famous hot springs and is one of the leading onsen destinations in the country. It boasts a long history, said to have been discovered as early as the Kofun period (approx. 3rd to 6th centuries AD), and has long been cherished as a therapeutic bathing site. Located at the foot of Mt. Kusatsu-Shirane, it benefits from the mountain's bounty, with a natural hot spring discharge volume of over 32,000 liters per minute, boasting the highest natural discharge volume in Japan (*1). The culture born from the hot springs, such as the steaming Yubatake, the traditional "Yumomi" stirring of the hot spring water, and the communal baths beloved by locals, has taken root, attracting many visitors throughout the year.
*1: Source: Kusatsu Onsen Tourism Association HP
Property Overview
Facility Name: Hoshino Resorts KAI Kusatsu
Number of Guest Rooms: 94
Ancillary Facilities: Front desk, shop, dining area, bathhouse, lounge, KAI Cultural Discovery hall, courtyard
Scheduled Opening: Spring 2026
Scheduled Start of Reservations: Fall 2025
Development Overview
Building Area: 3,690 m2
Total Floor Area: 11,857 m2
Land Area: 111,844 m2
Basic Architectural Design: Tatsuro Sasaki Architects' Office Co., Ltd.
LS Basic Design: SEA BASS Implementation Design and Construction: Maeda Corporation
About KAI
KAI is a hot spring ryokan brand operated by Hoshino Resorts, with 23 properties nationwide. With the theme "Authentic yet New," KAI pursues hospitality that caters to modern needs while preserving the changing seasons, Japanese aesthetics, and traditions. A key feature is the KAI Cultural Discovery, which offers experiences of local traditional culture and crafts, and the KAI Signature Rooms, guest rooms that incorporate local culture. In August 2025, KAI Hakone, located in Hakone Yumoto Onsen, Kanagawa Prefecture, will reopen after renovations, and in the spring of 2026, KAI Kusatsu will newly open in Kusatsu Onsen, Gunma Prefecture.
URL: https://hoshinoresorts.com/en/brands/kai/
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