The file skyrim_trans.xls contains data taken from the Google Docs spreadsheets 
that can be found from the following start point:
https://docs.google.com/spreadsheet/ccc?key=0ApfKCgi6l8EJdFBnNjRTMjR1WU90ZjBfbDM0eGc5RGc&hl=ja#gid=10

The Japanese translations on those files are freely available and written by 
anonymous Japanese translators.