A: This is decided by law in Japan. There are 3 conditions to why real estate apply to the law: property land is not contacted to registered street, the front street does not have 4 meter width, or over 2 meter of property land is not contacted to registered street.
Please know that this only mean that constructing newly built house is not possible. Renovation will be possible.
Advantage will be that real estate appraisal value will be low. This makes the real estate price reasonable for customers to purchase. Also, the real estate tax, which you will have to pay every year, will be lower compared to other real estate with same condition, but does not apply to the law.
Disadvantage will be that purchaser will not be able to get mortgage to purchase the real estate. This is the same when selling to next prospective purchaser.
I often see the phrase "building cannot be rebuilt after becoming flat land", but how is this decided? Any advantage? disadvantage?