To add to what "php at nospam-qualystem dot com" has mentioned.
Some Japanese Encoding System (shift-jis) encode characters like 予 with ASCII pairs "975C". (5C is ASCII for backslash)
Thus when reading those characters from files (saved as shift-jis) in system with magic_quotes_runtime enabled, the characeter is turned into 予\ (equivalent ASCII "975C5C")
予定 is turned into 予\定