Based on the light novel series, Yuki Yuna Is a Hero -Chapter of Washio Sumi takes place two years prior to the main series and tells the back story of one of its central characters.
Happy birthday to Yuki Yuna, whose birthday is March 21 as is appropriate to her spring/cherry blossom motif.
A second season of Yuki Yuna Is a Hero will begin broadcasting in October of this year.