I wouldn't recommend using that. You can add suffixes in SetParam using Tools > Change Aliases and type %a[YOUR SUFFIX] into Renaming Rule.
If you need to convert files from Shift-JIS to UTF-8 for any other reason in the future, you can do so with a decent text editor like Atom. Set the encoding to Shift-JIS to get the original Japanese characters, copy all the text, change the encoding to UTF-8, and paste the text back in to save it in unicode.