Any book store. They're a little hard to find though. Sometimes they're with the art books or on the sides of the shelves near the manga, or stored in the back somwhere so you have to ask someone working there. 0.0
It's 12 little books that feature interviews, illustrations, some never before seen manga, revies, and chess pieces. : 3 The Mokonas are pawns. The white one has an apple and the black one has a bottle of beer. XD