unzoned area; white zone
Technical term in Japanese urban planning for land outside designated zoning areas, where development is generally restricted.
Because this land is designated as an unzoned area, there are restrictions on building use.
Urbanization control area where development is strictly limited; 白地地域 is a broader category that includes such areas but also other unzoned land.
Compound of 白地 (しろじ, 'blank' or 'white') and 地域 (ちいき, 'area'), referring to land that is 'blank' on zoning maps, i.e., not assigned a specific land-use designation.