Depends on what you want/need with this UTAU.
Did you download UTAU in the correct locale or do you still
see jibberish? How much Japanese do you know? Do you want
to start with a basic Japanese bank or what?
If
1] you're comfortable enough around Japanese/hiragana then almost any
basic UTAU will do. CV is probably better to start with
than VCV, but that's just my opinion. I'd just go grab
a popular one that you like in that case, such as Teto.
(On Japanese sites I believe it goes something like
single sound = cv and renzouku/continous sound = vcv)
2] you don't know much Japanese but want to start with a Japanese
bank, then find a romaji CV bank. Uhh, many overseas
banks are romaji with hiragana aliases or vice-versa.
Find one of these, grab some usts and go~
3] you would prefer to start with a language you're more familiar
with then I'm sure people here can refer you to a bank
of such language. I'm not familiar with a lot of them
though.
If it's English you're looking for
then I hesitate to suggest the CV-VC banks as there's
a bit of a learning curve with them imho; if anything
I'd say Camila Melodia because her English sounds
are pretty straight-forward while her Japanese sounds
are in romaji (and aliased to also be compatible with
hiragana if I remember correctly).
If you have any questions feel free to ask me! :]
If you're just starting UTAU I'll tell you that two of the first things
you'll want to really learn about are flags and mod.