There's a little tips'n'tricks to export model from kk and make it work on mmd.
to make exported model work on mmd:
1) open model on pmx editor
2) go to "display plane" tab
3) delete all "-1" elements (probably #4 upper body 4,5,6 and #5 arms 2,4,8,10)
4) switch encoding tab to UTF-16
5) save model
after that you able to load model on mmd/mmm without crashing
warning #1: exported model has about 700-900 bones. you can't handle it with usual way, but most of existing motions/poses are suitable.
warning #2: exported model has few ten thousands of vertex/faces and may destroy your computer. you need good cpu/gpu for that.
warning #3: pmx plugin not able to export nipples texture.
warning #4: you need alot of weight/uv drawing on pmxe to avoid clipping.
warning #5: exported model has 500+++ morphs. and all of it are on "eyebrows" tab. you need to change on pmxe it if wanna use.
Vカツ / V-Katsu game (free)
Koikatsu / Koikatu / コイカツ！ game (￥9,800円)
KK Hongfire thread: