Saunas Are Squeezed Into These 275-Square-Foot Japanese Tiny Homes

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Japanese architects Kazumasa Takada and Yuriko Yagi took an unconventional approach to developing their practice. After meeting in Copenhagen in 2017 and soon after establishing their studio, PAN-PROJECTS, they spent the first few years designing experiments like a pavilion built from upcycled paper and a series of floating public installations. But these seemingly offbeat ideas held a greater significance, shares Takada, who says they were "early attempts to test how modest architecture could frame collective experiences and connect directly to its context." Recognizing a kindred spirit in PAN-PROJECTS and the ideas they stood for, Earthboat, a Japanese hospitality developer specializing in nature retreats, asked them to design something small that could be easily set up on remote sites.

The result was a new tiny home, itself named Earthboat, "a small, self-contained wooden accommodation designed for simple stays in nature," says Takada. Later, he and Yagi got the green light to design a second mobile retreat for the developer—what would become Earthboat Cave. Here, we talk to Takada about what sets this iteration apart, as well as what’s next for their partnership.

What exactly is the Earthboat Cave?

It’s a small movable accommodation made of Japanese cedar, and the first one is located in the lakeside forest of Shirakabako, Japan. The project offers a quiet retreat where people can pause, rest, and reconnect with nature. It proposes a calm form of hospitality rooted in simplicity and proximity to nature, reflecting the broader Earthboat vision of a nature escape.

What qualities set the cabin apart?

It’s designed to support life outdoors rather than pull people inside a compact cabin. Its layout, outdoor access, and sauna encourage guests to stay close to the landscape. The building sits on adjustable jacks without typical foundations, so the ground remains undamaged. Natural thermal comfort is achieved through solid Japanese cedar CLT rather than synthetic insulation. Chemical-based materials are minimized.

What did Earthboat ask for in terms of the design?

Earthboat wanted an accommodation that could be placed directly in natural landscapes, remain movable, and offer a calm, outdoor-oriented experience.

The material approach also matched their priorities. The cabin is made almost entirely from timber, making most of it biodegradable, and the use of CLT allows efficient factory precutting and production. This combination of mobility, environmental care, and comfort aligns closely with Earthboat’s vision for nature-based hospitality.

What does the base model cost and what does that pricing include?

The pricing varies depending on the location and difficulty of placing the unit on-site. For accessible sites, costs remain lower; for remote or high-altitude locations such as ski resorts, delivery and setup become more complex and therefore more expensive.

But to provide an overview of the potential pricing: the mobile cabin unit costs roughly U.S. $77,000, and transportation from Tokyo to Nagano would cost around $3,200. On-site construction and ground work (including landscape, electricity, plumbing, etc.) would cost upwards of $12,900.

What aspects of the design can a client customize?

The core architectural structure remains consistent, but interior elements such as furniture, decorative items, and small accessories can be adjusted to suit the specific concept of each location or an operator’s preferences.

How long can a client expect the process to take after they put down a deposit?

The timeframe depends heavily on the conditions of the site. If the location is easy to access and requires minimal preparation, the process can be completed within a few months. For remote or complex sites, especially those in mountainous areas, additional feasibility checks and coordination are required, which can extend the timeline to around a year.

Earthboat reviews each site individually, so the schedule is confirmed on a case-by-case basis.

Where are your tiny homes currently available? Are there any plans to expand?

The units are manufactured near Tokyo and delivered across Japan. And yes, Earthboat is preparing to expand beyond Japan. They are currently looking into opportunities in the United States and Australia, where more suitable natural environments and outdoor-living cultures make the concept suitable. These plans are in development but are not expected to be realized for another one or two years.

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