As far as I know, 'new half' refers to those who have added 'female' breasts to make a kind of upper half female-like look, with the lower half being male as usual. This medical procedure is fairly new, and having it done as commonly as it is, is fairly new, so. . . new.
It's not going the whole transvestite 10 yards.
I recall that last year, or so, in one of these 'muscle man' physical-strength-testing obsticle course races on TV, one 'new half' competed. Unlike almost all the others, he wore more of a bra-like top. He looked a bit, well, gross? is the right word? Not femine at all, except for the breasts. Oh...well,...that's new halves for you, 窶堋ゥ窶堙遺?塲ク. . . ?