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Amazon Link: http://tinyurl.com/q9hhr88
Official Publisher Link w/info: http://www.hayakawa-online.co.jp/product/books/21114.html
Miura did the cover illustration for a June publication of a Guin Saga tribute book. As fans will know, Guin Saga was a long-running fantasy novel series by Kaoru Kurimoto that was a big inspiration for Miura in creating Berserk. Kurimoto passed away in 2009 at age 56 of pancreatic cancer, having completed 130 volumes in her series.
From what I can gather of its description, this tribute book, the eighth in a series, gathers short stories from different writers to continue her story.