Yuuki Yuuna wa Yuusha de Aru: Washio Sumi no Shou  

結城友奈は勇者である -鷲尾須美の章-

In 298 years after the time of gods, three elementary school girls named Sumi Washio, Sonoko Nogi, and Gin Minowa are given a crucial assignment. Their objective is to become heroes and defend Shinju-sama, the god tree that safeguards Shikoku, the only region on Earth where life persists. However, they are unaware of the immense cost this battle will entail.