washio sumi wa yuusha de aru
A 2014 light novel written by Takahiro and illustrated by BUNBUN. A part of the Yuusha de Aru franchise, it takes place 2 years before the events of Yuuki Yuuna wa Yuusha de Aru. It received an anime adaptation as part of the second season of Yuuki Yuuna wa Yuusha de Aru in 2017.