Washio Sumi wa Yuusha dearu, prequel novel of Yuuki Yuuna
Note that the novel were serializing on Dengeki G's Magazine (monthly) from April30(,2014) to Nov29, which form a total of 8 chapters and will be gather together and publish as a book in Japanese by Dec20 with one more additional chapters. As of Dec12, 6 chapters have been translated on 4chan.
Washio sumi novel:
ch1 p.1 https://archive.moe/a/thread/116135089/#116144248
ch1 p.2-3 https://archive.moe/a/thread/117000642/#117090114
ch1 p.4-8 https://archive.moe/a/thread/117209264/#117235814
ch2 https://archive.moe/a/thread/117518875/
ch3 https://archive.moe/a/thread/117792620/#117807123
ch4 https://archive.moe/a/thread/117900925/#117910907
ch5 https://archive.moe/a/thread/118101546/#118107664
ch6 https://archive.moe/a/thread/118133302/#118143289
further translation updates might appear on 4chan soon but this paste would not be updated and you might want to check for them manually.

hero dairies that appear before each chapter of washio sumi:
https://archive.moe/a/thread/117563345/#117577784
ch8 summary:
http://forums.animesuki.com/showthread.php?p=5354011#post5354011