Here's Haku's model, not sure where to find Luka
https://mmda.booru.org/index.php?page=post&s=view&id=263

Looks like a scam so removed comment

I will look to see if I still have luka succubus and if I Do and you have Discord I can send you her I use the same name as here.
I found her and split her into 2 parts now I can share on Discord 1st is almost all 2nd is her legs Unzip then put all parts in folder happy happy Luka succubus time

Here are other models but made by another creator if you are interested:
https://mmda.booru.org/index.php?page=post&s=view&id=262
https://mmda.booru.org/index.php?page=post&s=view&id=263

https://mmda.booru.org/index.php?page=post&s=view&id=762

Here I give you the link of a complete pack made by another creator
https://www.deviantart.com/k-manoc1/art/MMD-Model-Pack-TDA-Succubus-Mode...

ingenioabc is the pack R18 Nudable {full body}

the second and third links have version r-18, the other links do not.

Thank You for letting Me Know ingenioabc

This pack of models that Phoenix2 made a while back includes some succubus models.
https://mega.nz/#!HkYWVQQT!9x5YtfuYoTmLTnRPksAtxVfyjzTFa9u0zlW6bqyOaVo