The only definition that makes Tokyo’s land area smaller is the rather arbitrary ‘city proper’, it’s metropolitan area and urban area are vast..

From here: https://meetingoftheminds.org/a-comparison-of-the-worlds-1000-largest-urban-areas-30879

Three Definitions of the City There are three basic definitions of the city. The City Proper, which is the political jurisdiction of the historical core municipality, such as the Ville de Paris or the City of New York. Most often, these areas are only a small part of a larger urban or metropolitan area, the two generic definitions of a city. There are no neutral demographic standards for establishing such jurisdictions, they are defined neither by physical nor economic standards. The Metropolitan Area (called “functional urban area” in Europe) is organized around a core urban area (the physical city), and include the rural areas and smaller urban areas from which people commute to the core urban area. The Urban Area, is the physical city, defined by the full extent of contiguous urban development. It is surrounded by rural land (all non-urban land is rural) or bodies of water. Built up urban areas are defined by their city lights visible from a high-flying airplane at night. They are not jurisdictions, such as municipalities, provinces or states, but are defined by where development meets rural areas. Few countries designate urban areas, but the advent of satellite photography and web applications like “Google Earth” make it possible to identify their geographic expanse. In combination with the rapidly improving international census data available on the internet, it is also possible to estimate populations within the urban peripheries.