SEGA has released an art book for Valkyria Revolution, their recently released spinoff game from the Valkyria Chronicles series. The art book contains a total of 240 pages, and aside from artwork (ranging from CG to sketches) it also has interviews with the developers and artists, as well as a timeline for the major events of the Liberation War. The art book is currently available on Amazon Japan.
Aside from the art book, there’s also a special collaboration artwork that was recently created for Valkyria Revolution and Gust’s Blue Reflection. Both games had their respective character designers draw one of the other game’s main characters. In particular, Kishida Mel drew Ophelia from Valkyria Revolution, while Hiroshi Kiyohara drew Noriko Shirai from Blue Reflection (just barely keeping it safe for work). You can view preview pages from the artbook, as well as a wallpaper based on the collaboration artwork below.
Valkyria Revolution Art Book preview pages
Valkyria Revolution and Blue Reflection Collaboration Wallpaper
Sources: Dengeki Online, Valkyria: Azure Revolution blog, Blue Reflection collaboration webpage