There has been concern in some quarters of the Japanese media about Chinese interest in land and real estate. New Zealand recently introduced controversial restrictions on overseas investment in farmland, after a Chinese firm bid for the country's biggest private dairy farm, and it seems the government is considering a similar policy in Japan. The Prime Minister has indicated he favours such action and has asked the Ministry of Justice to look into the matter. There was a 1925 law which prohibited sales of land if it was not in the national interest but this was repealed after the war. It didn't specify and areas or categories of land which were essential to national security but any new legislation might do so. However, it may not be limited to forestry and agricultural assets since, in his comments, Kan wondered about the effect of foreigner investors owning Ginza.
Source (Japanese)