Not atypical of central Tokyo, the site for this private residence is an urban gap left over from relentless subdivisioning, a 22m deep yet only 4.7m wide strip perched between built masses.When the brief asked for a wide open living space where breathing within the confines of the city was possible, we proposed an architecture of the exterior that claims the space around it by extending beyond its limits.The site's limitation is turned into an asset: a context of nondescript neighbours is ignored and at the same time appropriated to defy the site's narrowness.The building is a departure from understanding housing as enclosing: The urban exterior continues in an open fold of fluidly interconnected spaces for living in the interior of the exterior.The building's only really visible elevation is its cross section, a cut through the thin folded plane unveiling its dichotomy: a house without inside.Behind the transparent lightness visible in the cross section lies a structural concept developed with Masato Araya. It is an ingenious composition of structural principles that play together strikingly: they break up each other's rigidity and make the building impossibly light. The building's fineness establishes an intriguing neighbour-neighbour relationship of mass versus lightness, enclosed versus open. Moving through the building reveals strikingly different atmospheres along the three levels’ alternating orientations. As there are no fixed partitions, the depth of each level is fully perceived, the site's proportions emphasised. Soft fabrics countering the hardness of the concrete add layers of ambiguous spatial nuances.In folding a single plane, the house's three levels open up outward on alternate sides, extending towards and including their surroundings. Being able to live with the seasons in the middle of today's Tokyo is experienced as a true luxury.