Fyi this artist apparently made another artbook: https://www.toranoana.jp/mailorder/article/04/0030/44/14/040030441478.html
It includes a bunch of poses he drew for a Shana android game called "封絶バトル:" https://play.google.com/store/apps/details?id=jp.mobage.am.g12021837.lite&hl=ja