[dirtyroboto]

When the Japanese build a new house they get a monk to perform a blessing ritual on the vacant lot. Kind of to ask god's permission to build there and also to ensure the land and house are free of bad energy.
Energy or in this case "bad energy" is the reason they don't want basements or cellars as part of the house.
For many Japanese, the idea of living underground is not good for the spirit. The sub-earth will drain your energy and impart bad energy to you, your house and your family.

Just having part of your home underground is like having a conductor of bad energy that will bring all manor of bad things to your family. This is how the Japanese think about these things.

By implication, if you store things in the basement they will collect bad energy. Everytime you need to remove an item from the basement, you will requre the presence of a monk.