Yuuki Yuuna wa Yuusha de Aru is a Japanese anime series that follows the story of Yuuna Yuuki, an ordinary middle school student who becomes a hero to fight mysterious beings known as Vertexes. Set in a world where the Hero Club is tasked with protecting the divine tree, the series explores themes of friendship, bravery, and sacrifice, as Yuuna and her friends face various challenges and uncover secrets about their world.