The Essential UTAU Toolkit is a collection of programs used for problems involving romaji/hiragana differences, as well as locale issues.
The programs work on code released from The Code Project, and involve text replacement. They work on a byte-by-byte level, allowing the programs to work even on computers that do not have Japanese locale installed. All of the programs leave backup copies to ensure that there is no permanent damage done.
The programs run on Java, requiring that a recent version of Java be installed.
The UST converter can convert .ust files from hiragana to romaji or vice versa. This allows use of the files on a voicebank encoded in kana or romaji. Also, even if Japanese locale is not installed, a romaji .ust file converted to mojibake will work with a voicebank encoded in mojibake.
As diphone arrow signs occasionally do not work on computers without Japanese locale, there is also an option to remove diphone marks or to convert them to a state usable by normal computers.
The voicebank aliaser can add hiragana aliases to a romaji voicebank or romaji aliases to a hiragana voicebank. It can do the same for voicebanks with diphone marks, along with converting aliases with diphone marks to a state usable by normal computers.
The Essential UTAU Toolkit works on Windows XP and Vista, but has been known to give difficulties in Windows 7 (this has not yet been fixed). However, some people with Windows 7 have been able to successfully use it.
Some people who have been unable to use it in Windows 7 have gotten the converter to work by manually dragging and dropping the file on top of the correct batch file (in the case of USTs, after having renamed it). This has not been formally tested, but has yielded results.
The latest version of The Essential UTAU Toolkit, along with older versions, may be found at the Fuzzle-san UTAU website.
Edit: The Website is no longer up, Therefore The Essential Utau Toolkit is no longer available