Last night NHK’s documentary series A to Z covered the phenomenon of abandoned houses. Based on local government statistics, it’s assumed that there are 100,400 unoccupied houses in Tokyo alone, a 40 percent increase since 1998. The number of abandoned homes in Tokyo increases at a rate of about 3,000 a year. NHK limited its coverage to the mostly residential areas of Setagaya and Suginami Wards, finding “at least” 500 houses that looked to be abandoned, of which they isolated 103 for more detailed study.

Study in this case meant talking to neighbors and local officials about the state of these homes, most of which were in severe states of disrepair, as well as finding out who the owners were and why they weren’t living there or keeping the properites up. Understandably, neighbors were quite concerned, not just with the eyesore aspects–some properties were magnets for refuse and overgrown with weeds and vines–but because they were fire hazards. Abandoned homes are often the targets of arsonists.

Ward officials receive complaints from neighbors about abandoned homes on a daily basis, but legally there is little they can do. It’s a Catch-22 situation: They need permission from the owner of a property before they can set foot on it, and in most cases they cannot locate the owner. In some instances, the owner has died and no heirs can be found; or, as in the case of one woman, a painter who died several years ago, her son was eventually located by NHK and said he had had “no connection” with his mother for many years. One owner of a house in Adachi Ward died with a lot of debt, so it’s assumed that his relatives have not come forward to claim the property because they are afraid they will have to assume that debt along with the property.

However, in some cases the neglect is on purpose. Officials know of some cases where the title of a property was taken over by a relative after the death of the owner or was sold to a third party. These new owners are simply waiting for the value of the plots to increase so that they can sell them for profit, but in the meantime they aren’t maintaining the properties. Of course, the houses in almost all these cases are worth zero, but in any of the 23 wards of Tokyo the land on which they stand could be quite valuable. One property in Setagaya that NHK checked was worth ¥200 million, but no one has seen the owner in at least ten years.