This is a Japanese-language illustration (art) book.
A comprehensive overview of this artist's work from 1997 to 2010. (He uses Choco mostly for his doujinshi work, while Koichi Mugitani is for his more professional art.) This limited set includes:
Two books - Color and Monochorme. Each is 112 pages long, and as the titles imply, contain color and B&W illustrations, respectively.
A DVD ROM.
3 Illustration sheets
This is a must have for any collection!