I have a stupid question, how official do Vocaloid characters need to be? Basically, are Haku Yowane and Neru Akita elegable? They are fanmades acknowledged by Crypton Future Media and are included in the Project Diva series of video games.

Both have enough songs to otherwise meet the Vocaloid requirements.

EDIT: Additionally, Haku herself at least has her own song in the Of Evil series, and in fact it is one of the longer ones.