Board Thread:Off-Topic Discussion/@comment-66.87.128.137-20130821231548/@comment-53539-20130824122650

Aye, its not unheard of even outside of Vocaloid either.

As a One Piece fan, "Luffy" is the official spelling of the name as confirmed by the mangaka Oda himself, so any other version of the name you see such as "rufi, Lufi, Ruffy" are incorrect.

Again though, one can't expect the Japanese to be experts of the English language so there are sometimes mistakes to be found... But I doubt any of the versions of the names MrMattewz listed are incorrect. I usually say that if you don't know the name, it is pronounced how the vocaloid itself attempts to sound out its own name when you type it out in its synthesizer.