Files exported from Moodle in .csv format to do not handle UTF8 characters properly. Do this:
1) Create a new database activity.
2) Create two fields, "name" and "address"
3) Copy and paste the following data into two successive records:
name: 佐藤 宏 address: 〒603 京都市北区上賀茂本山999
name: 黒田 泰史 address: 〒603 京都市北区上賀茂本山123
4) Export the data as .csv (I used the tab delimiter)
5) View the resulting spreadsheet
This appears to be a problem not only with the database component, but rather with excel export from any Moodle module. See the attached composite screenshot.