Soft concrete may be an oxymoron, but Ellipse Sky, a four-story residential building designed for an obstetrician, his family, and several tenants, deftly pokes holes in that notion. A concrete box on the western edge of Tokyo, the house is the first freestanding structure by Keiko + Manabu, a young design duo specializing in commercial interiors. The pair teamed with engineer Akira Suzuki to craft a building that mollifies the hard material with swooping arches, graceful details, and walls as smooth as a baby's bottom.
The decision to build with concrete was a given from the start when the client purchased a plot near his birthing center and invited three firms'all with female principals'to participate in a design competition. Approaching the brief with the vision and sensitivity of interior designers, partners Keiko Uchiyama and Manabu Sawase presented a large-scale (1:20), easy-to-understand model and landed the commission. 'This is a very important scale for us,' says Uchiyama. 'It is where you can imagine the inside from the outside.'