The artist had to delete his old galleries on Pixiv, due to the guidelines and uploaded them now in new Collection.
If you download the chapter via the mega link that is given in his collection, then there is an unused picture in the folder as well as a few reference pictures that he has used. Certainly not planned, but if you want to know what he looked at for it, you can download it there.

Here is the Pixiv link to the collection:
https://www.pixiv.net/en/artworks/104892244

The artist says that all his works are free and freely available, but if you still want to give him a little support:
https://www.buymeacoffee.com/ManicoCoffee