Apartment project at the site with tight frontage in central Tokyo. Six voids are meeting the local evacuation code and supply the daylight and airflow, while retaining density and thus enhancing rents. The studio flats in this complex arrange their bath areas towards the core of their volume and corridor along an exterior wall. The respective corridors internally connect the six voids as thoroughfares of natural ventilation from the street-front to the back. A loft and steps for cats are located in the vicinity of windows facing the voids and provides comfort for human residents and cats.