To me it looks like one of the regular 1/6 heads, it could make more business sense to use heads already available, some of the 1/6 girls have small neck knobs. The 23 & 21 dolls fit any of the 1/6 heads.
I've been wanting one of these cuties for a while >w< they said April now they say May lol there's a link to a 47cm parabox original giving her a cuddle >///< supa kawaii!