Hello everyone!
The Cinderella Phenomenon Artbook is now available for only 4.99 USD.
It contains 123 pages of in-game images, promotional artworks and commentaries.

http://store.steampowered.com/app/653580/Cinderella_Phenomenon_Digital_Artbook/

For those who don't know how to access the artbook, it should be inside the game folder itself.
If you right click on Cinderella Phenomenon and click properties -> local files -> browse local files, you should have a file named Cinderella Phenomenon artbook or something similar.

Thank you so much!