Overseas buyers look at aerial photographs and conclude a plot is flat. Japan built extensively into its hills, and a great deal of what looks like level ground is level because somebody made it so.

The retaining wall underneath a hillside plot is the largest concealed liability on the property, and replacing one can cost more than the building above it.

These guides cover what to check on the ground itself, and what the record says about the land.

What holds the land up

• The wall holding up the land is part of what you are buying. Approval records, weep holes you can count, and the cost of replacement.

What the land is

• The land area in the listing is a historical record. Registered versus surveyed area, and boundary markers on the ground.
• The land category can stop the sale entirely. When part of the plot is farmland, and the permission it needs.
• The land you can never build on again. The road frontage rule, and why some plots can never be rebuilt on.

Ground and hazard

• Japan's hazard maps and what your broker must show you. Which hazards are disclosed before contract, and which are not.
• Two dates decide how a house behaves in an earthquake. The 2000 revision, which tied foundations to ground investigation.
• The morning after a typhoon, the damage is not where you are looking. Checking slopes and retaining walls after heavy rain.

Climate

• Owning a house where it snows properly. Snow as a structural load, and what winter demands of a site.

If you are earlier in the process, start with the full guide to buying property in Japan as a foreign buyer.