Taking place during the holy year 300, the story tracks the life of Yuuna Yuuki, an average 2nd-year middle schooler and member of the "Hero Club." Their primary focus is dealing with an elusive being referred to as the "Vertex." Simultaneously, this program was broadcast alongside the movie "Yuuki Yuuna wa Yuusha de Aru: Washio Sumi no Shou Movie 2 - Tamashii."