I used to be reaaaaally into MMD back in the day and I could never bear to delete my files. Now i'm into avatar creation and they're useful again, so I thought I'd share with all of you lovely people! 
You will need to have the knowledge to turn a .pmd/.pmx file into an .fbx or a .vrm into a .anim file, but I'm sure there'll be some useful things for even you non-blender folks like textures etc
(warning: these are terribly organised, there will be duplicates and probably empty folders, direct your anger for this towards 13 year old me 
)
(another warning: There is absolutely NSFW content in here somewhere because I remember downloading a pack full of it as a little jorny teenager, open at your own risk)
Asset Folder: https://mega.nz/folder/sBNzBZLQ#6If1kXO-ewcR5f-UFj-DPw
Pictures of the models I catalogued before I gave up: https://mega.nz/folder/QF8kELDZ#rIolmKtSifmOnqmKs5WxdQ