Guilty Crown Lost Xmas was the game that base on the "Lost Christmas" incident that happen in the Guilty Crown animation, which mean the prequel of the anime series. Original source was found at here. At the same time I have gather some other source at below as well.
Another calendar found for the Ao no Exorcist or Blue Exorcist, the size of this pack abit big compare to previous two calendar, but well maybe better quality. Original found via this forum, get the copy via below if you want.