Kengo Kuma uses stones from a Japanese hot spring to design this one-bedroom inn

Japanese architect Kengo Kuma's signature experimentation with contextual forms and new materials to replace concrete and steel finds a robust reflection in a recent small hospitality project executed by his Tokyo-based eponymous practice. The firm was commissioned to design a one room ryokan (traditional Japanese inn) in a small town known to house one of Japan's most famous hot springs. Located 200 kilometers northwest of Tokyo, Kusatsu Onsen, where the ryokan is located, boasts of the largest flowing water volume of all hot springs in Japan.

Opposite one of these hot springs, on a corner of a street, the ryokan is erected as an extension of the surrounding landscape. One encounters the two-storey building as a sculptural form of contradictions as sharp black walls are softened by curve geometries. "To further harmonise with the landscape," says the design team, "curve geometries that resonate with the soft movement of the steam rising from the hot springs govern how we arranged the use of local materials."

Interestingly, the architects have one such location-specific material as a defining feature of the architecture. Asama stones which are found on the bed of the hot springs are placed in rows on the ryokan’s exterior skin. According to the Japanese practice, this intervention was meant to create a three-dimensional landscape by making the architecture meet its context.

Flanked by a typical Japanese morphology of hotels and ryokans which have their names written in big and bold typography to pull visitors from afar, the sporadic rows of irregular stones on this cavern-like form looks more like a misfit in its neighbourhood.

The curved geometry on the lower part of the façade gives way to the entry into the ryokan. Traditionally ryokans are more than just a place to sleep. These are designed for people to experience traditional Japanese lifestyle and hospitality by incorporating elements like tatami rooms, futon beds, Japanese style baths, and facilities to savour an assortment of local cuisine. Stepping away from the conventional side, this ryokan is an ode to the contemporary Japanese living. The ground floor is designed as a minimalist restaurant space with large glass windows visually filtering the everyday life of the street inside.

The upper floor is the resting nest of the ryokan, accessed via an external staircase. The interiors reveal a partial pitched wooden ceiling with exposed angular rafters, jet black walls, and interesting tactile decorations on surfaces. The layout of the open-ended space is divided into three zones – the bath, the living area, and the bedroom. Lighting design inside the double height interiors follows the idea of highlighting the many textures of the space. While higher pendants are suspended down the ceiling, for the walls LED strips with diffusers create an inconsistent milky effect, much like painting a wall in a gradient wash.

Though the expression of the Japanese architecture comes across as quite chic and contemporary, it has been crafted using traditional materials and techniques including Asama stone terrazzo, Japanese washi paper mixed with crushed local stones, and local tiles. Speaking of the intent behind this ensuing contradiction, the design team concludes, "By incorporating material and geometrical elements of Yubatake hot springs throughout the building, we condensed the materiality of the historic town of Kusatsu in this small building.”