This might help.
Japanese Hiragana 
If you will notice it's "fu" instead of "hu".
While I am failing miserably at learning Japanese I have done a great deal of reading on the pronunciation. (I want to know what they're
saying!) Every book I have read says that the sound is actually halfway between an F and an H. Sort of like how we combine T and H to make "th". It's an interesting sound (I have a live CD to help with pronunciation I can listen to) but if you can't do it and have to pick one or the other the "fu" is closer. As a result though when translated to english you will find it spelled both "hu" and "fu" but the "fu" is the accepted translation.
In my opinion if your going to be strictly phonetic it should be "fhu" but when has the english language ever been strictly phonetic? lol