Heroes are female elementary or junior high students that are specifically selected by the Taisha. Their goal is to battle and defeat the Vertexes that are trying to destroy the Shinju, which is the guardian deity of humanity.
There are 6 Heroes present in Yuki Yuna is a Hero, 3 in Washio Sumi is a Hero, 5 in Nogi Wakaba is a Hero, and 2 other heroes in Yuki Yuna is a Hero: A Sparkling Flower.