Yuki Yuna wa Yuusha de Aru is a Japanese anime series that follows the story of Yuna Yuki, an ordinary middle school student who becomes a hero to fight mysterious entities called Vertexes. Set in a world where a divine tree protects humanity, Yuna and her friends are chosen by a secret organization to defend their world. The series explores themes of friendship, courage, and sacrifice as the girls navigate their new responsibilities and the challenges they face as heroes.