This residential development comprising 17 leased condominium units is situated on the north side of JR Nakano Station in Tokyo, and forms part of a large-scale redevelopment project adjoining an expansive urban park. The flat slab construction method employs completely double floors and ceilings, providing the ultimate in long-life "skeleton infill" (SI) housing. By utilizing a full-surround balcony composed of an outer-grid frame of slender precast concrete columns, the design realizes open interior spaces with a 2.5m ceiling height while providing generous views of the surrounding park environment. The balcony eaves' precast concrete form uses a specific type of CO2-absorbing concrete for the first time in a building project. The building aims to create a prototype for a range of innovations in residential design and construction, with particular focus on the development of high-quality housing stock.