Maruni Wood Industry × ONE SAUNA Co-Develop Premium Furniture-Grade Sauna 'kupu sauna' — World's First Installation at Sosuikyo, Mie Prefecture
Key facts
- Maruni Wood Industry × ONE SAUNA Co-Develop Premium Furniture-Grade Sauna 'kupu sauna' — World's First Installation at Sosuikyo, Mie Prefecture
- The furniture-grade sauna 'kupu sauna,' co-developed by Maruni Wood Industry and ONE SAUNA, will be introduced for the first time globally at Sosuikyo, a luxury detached villa resort operated by Aquaignis in Mie Prefecture. Featuring distinct sauna experiences themed around wood and stone, reservations are open from July 4, 2026.
- Source: PR Times
- Date: June 16, 2026
Direct answer
The furniture-grade sauna 'kupu sauna,' co-developed by Maruni Wood Industry and ONE SAUNA, will be introduced for the first time globally at Sosuikyo, a luxury detached villa resort operated by Aquaignis in Mie Prefecture. Featuring distinct sauna experiences themed around wood and stone, reservations are open from July 4, 2026.
- Citation
- Maruni Wood Industry × ONE SAUNA Co-Develop Premium Furniture-Grade Sauna 'kupu sauna' — World's First Installation at Sosuikyo, Mie Prefecture (June 16, 2026), PR Times
- Source
- PR Times
- Date
- June 16, 2026
The furniture-grade sauna 'kupu sauna,' co-developed by Maruni Wood Industry and ONE SAUNA, will be introduced for the first time globally at Sosuikyo, a luxury detached villa resort operated by Aquaignis in Mie Prefecture. Featuring distinct sauna experiences themed around wood and stone, reservations are open from July 4, 2026.
📋 Article Processing Timeline
- 📰 Published: June 16, 2026 at 19:00
- 🔍 Collected: June 16, 2026 at 21:13 (2h 13m after Published)
- 🤖 AI Analyzed: June 16, 2026 at 21:33 (20 min after Collected)
Maruni Wood Industry Co., Ltd. (Hiroshima City, Hiroshima Prefecture; President & CEO: Hiroshi Yamanaka) and Libertyship Co., Ltd. (Miyazaki City, Miyazaki Prefecture; CEO: Haruya Agematsu, operator of sauna brand 'ONE SAUNA') have jointly developed a furniture-grade sauna called 'kupu sauna.' It has been decided that this sauna will be introduced for the first time in the world at 'Aquaignis Bettei Yuno-Yama Sosuikyo,' a detached villa resort operated by Aquaignis Co., Ltd. (Chuo Ward, Tokyo; CEO: Tetsuya Tachibana).
The installation will take place in two villas: 'Kikoku,' themed around wood, and 'Sekirou,' themed around stone. Reservations are now being accepted for stays starting from July 4, 2026 (Saturday).
Key Highlights of the Introduction
World's first installation of a 'furniture-grade sauna' at a lodging facility, resulting from a collaboration between Maruni, a woodworking furniture manufacturer; product designer Wataru Kumano; and ONE SAUNA, a pioneer in domestically produced barrel saunas.
Unique sauna experiences tailored to the themes of each villa: 'Kikoku' and 'Sekirou.'
ONE SAUNA received the 2020 Good Design Award. The design philosophy of local production for local consumption is carried forward, utilizing Yoshino Hinoki from Nara to enhance fragrance, touch, and wood texture.
Equipped with ONE SAUNA's proprietary IoT sauna management system (Patent No. 7510172), which enables automated preheating, automatic heater cutoff linked to an emergency button, and automatic administrator alerts—ensuring comfort, energy efficiency, and safety.
About kupu sauna
Founded in Hiroshima in 1928, Maruni Wood Industry has developed furniture in collaboration with designers from Japan and abroad, guided by the motto 'industrialization of craftsmanship.' For this 'kupu sauna' project, product designer Wataru Kumano (principal of design office kumano) and ONE SAUNA, possessing expertise in thermal and sensory design for sauna development, have joined forces to apply Maruni's woodworking techniques—honed through furniture manufacturing—to the extreme environment of heat and steam.
The resulting 'kupu sauna' achieves both furniture-level finishing precision and functional and sculptural beauty designed by a product designer. Its signature half-dome curved structure is designed so that steam generated during löyly circulates along the curved inner surface of the dome and gently falls onto the bather's back, creating a one-of-a-kind sensory experience.
Interior rendering showing areas where high temperatures accumulate
Interior concept image
Overview of Installation at Sosuikyo — Sauna Experiences by Room Theme
'Aquaignis Bettei Yuno-Yama Sosuikyo' is a resort consisting of 12 detached villas, each offering guests the pleasure of 100% natural flowing hot spring water and high-quality cuisine. Each villa is designed around natural materials, and in alignment with this concept, 'kupu sauna' will be introduced in the two villas 'Kikoku' and 'Sekirou.'
Villa 'Kikoku' — Themed around Wood
A villa generously using domestic cedar for both interior and exterior finishes. Designed to allow guests to experience the softness and warmth of wood as a natural material and to feel a relaxed, unhurried pace.
- Sauna access via a wooden deck, creating a seamless flow
- Equipped with Maruni's 'Totoi Chair' (kupu sauna chair)
Villa 'Sekirou' — Themed around Stone
A villa featuring massive stones of 'Komonoshi,' quarried in Kumano Town, Mie Prefecture, placed at the entrance and in the living area. This space offers an extraordinary experience of touching stone and feeling its power through the skin.
- Includes a stone cold bath, enabling a full-cycle routine: sauna → stone cold bath → outdoor cooling
- Equipped with Maruni's 'Totoi Chair' (kupu sauna chair)
Company Profiles
■ Maruni Wood Industry Co., Ltd.
- Headquarters: 24 Shirasuna, Yuki-cho, Saeki-ku, Hiroshima City, Hiroshima Prefecture
- Founded: 1928
- Representative: President & CEO Hiroshi Yamanaka
- Business: Planning, manufacturing, and sales of furniture
- URL: https://www.maruni.com/
■ Libertyship Co., Ltd. (ONE SAUNA)
- Headquarters: 7275-1 Koe, Miyazaki City, Miyazaki Prefecture, Kodomo no Kuni
- Representative: CEO Haruya Agematsu
- Business: Sauna development and operation; sauna facility production; provision of the IoT sauna management system 'ONE SAUNA'
- Brand URL: https://onesauna.jp/
- Corporate URL: https://libertyship.jp/
■ Aquaignis Co., Ltd.
- Headquarters: 7F, Yoda Tadashi Building, 1-14-9 Kyobashi, Chuo Ward, Tokyo
- Representative: CEO Tetsuya Tachibana
- Business: Food and beverage; hot spring facilities; confectionery manufacturing; real estate
- Corporate URL: https://aquaignis-company.jp/
- Facility Name: Aquaignis Bettei Yuno-Yama Sosuikyo
- Facility Location: 4842-1 Komono, Komono-cho, Mie-gun, Mie Prefecture
- Facility URL: https://sosuikyo.com/
The installation will take place in two villas: 'Kikoku,' themed around wood, and 'Sekirou,' themed around stone. Reservations are now being accepted for stays starting from July 4, 2026 (Saturday).
Key Highlights of the Introduction
World's first installation of a 'furniture-grade sauna' at a lodging facility, resulting from a collaboration between Maruni, a woodworking furniture manufacturer; product designer Wataru Kumano; and ONE SAUNA, a pioneer in domestically produced barrel saunas.
Unique sauna experiences tailored to the themes of each villa: 'Kikoku' and 'Sekirou.'
ONE SAUNA received the 2020 Good Design Award. The design philosophy of local production for local consumption is carried forward, utilizing Yoshino Hinoki from Nara to enhance fragrance, touch, and wood texture.
Equipped with ONE SAUNA's proprietary IoT sauna management system (Patent No. 7510172), which enables automated preheating, automatic heater cutoff linked to an emergency button, and automatic administrator alerts—ensuring comfort, energy efficiency, and safety.
About kupu sauna
Founded in Hiroshima in 1928, Maruni Wood Industry has developed furniture in collaboration with designers from Japan and abroad, guided by the motto 'industrialization of craftsmanship.' For this 'kupu sauna' project, product designer Wataru Kumano (principal of design office kumano) and ONE SAUNA, possessing expertise in thermal and sensory design for sauna development, have joined forces to apply Maruni's woodworking techniques—honed through furniture manufacturing—to the extreme environment of heat and steam.
The resulting 'kupu sauna' achieves both furniture-level finishing precision and functional and sculptural beauty designed by a product designer. Its signature half-dome curved structure is designed so that steam generated during löyly circulates along the curved inner surface of the dome and gently falls onto the bather's back, creating a one-of-a-kind sensory experience.
Interior rendering showing areas where high temperatures accumulate
Interior concept image
Overview of Installation at Sosuikyo — Sauna Experiences by Room Theme
'Aquaignis Bettei Yuno-Yama Sosuikyo' is a resort consisting of 12 detached villas, each offering guests the pleasure of 100% natural flowing hot spring water and high-quality cuisine. Each villa is designed around natural materials, and in alignment with this concept, 'kupu sauna' will be introduced in the two villas 'Kikoku' and 'Sekirou.'
Villa 'Kikoku' — Themed around Wood
A villa generously using domestic cedar for both interior and exterior finishes. Designed to allow guests to experience the softness and warmth of wood as a natural material and to feel a relaxed, unhurried pace.
- Sauna access via a wooden deck, creating a seamless flow
- Equipped with Maruni's 'Totoi Chair' (kupu sauna chair)
Villa 'Sekirou' — Themed around Stone
A villa featuring massive stones of 'Komonoshi,' quarried in Kumano Town, Mie Prefecture, placed at the entrance and in the living area. This space offers an extraordinary experience of touching stone and feeling its power through the skin.
- Includes a stone cold bath, enabling a full-cycle routine: sauna → stone cold bath → outdoor cooling
- Equipped with Maruni's 'Totoi Chair' (kupu sauna chair)
Company Profiles
■ Maruni Wood Industry Co., Ltd.
- Headquarters: 24 Shirasuna, Yuki-cho, Saeki-ku, Hiroshima City, Hiroshima Prefecture
- Founded: 1928
- Representative: President & CEO Hiroshi Yamanaka
- Business: Planning, manufacturing, and sales of furniture
- URL: https://www.maruni.com/
■ Libertyship Co., Ltd. (ONE SAUNA)
- Headquarters: 7275-1 Koe, Miyazaki City, Miyazaki Prefecture, Kodomo no Kuni
- Representative: CEO Haruya Agematsu
- Business: Sauna development and operation; sauna facility production; provision of the IoT sauna management system 'ONE SAUNA'
- Brand URL: https://onesauna.jp/
- Corporate URL: https://libertyship.jp/
■ Aquaignis Co., Ltd.
- Headquarters: 7F, Yoda Tadashi Building, 1-14-9 Kyobashi, Chuo Ward, Tokyo
- Representative: CEO Tetsuya Tachibana
- Business: Food and beverage; hot spring facilities; confectionery manufacturing; real estate
- Corporate URL: https://aquaignis-company.jp/
- Facility Name: Aquaignis Bettei Yuno-Yama Sosuikyo
- Facility Location: 4842-1 Komono, Komono-cho, Mie-gun, Mie Prefecture
- Facility URL: https://sosuikyo.com/
FAQ
What is kupu sauna?
A furniture-grade sauna co-developed by Maruni and ONE SAUNA, combining design excellence with advanced functionality.
Where can I experience it?
At Sosuikyo, a luxury detached villa resort in Kumano, Mie Prefecture, available from July 4, 2026.
What are the features of kupu sauna?
Half-dome design for soft steam circulation and patented IoT system for safety, comfort, and energy efficiency.
How do the sauna experiences differ by room?
‘Kikoku’ uses domestic cedar for warmth; ‘Sekirou’ features local stone and cold bath for a powerful experience.
When can I make a reservation?
Reservations for stays from July 4, 2026 are now open via the official website.