There are some other books with the girls of Gessen : http://www.toranoana.jp/mailorder/article/04/0030/13/85/040030138596.html http://www.toranoana.jp/mailorder/article/04/0030/13/67/040030136774.html http://www.toranoana.jp/mailorder/article/04/0030/13/99/040030139942.html
I may upload one or more of them once they aren't any longer available.