Yuna Yuki is an ordinary middle school student. She gets up each day and gets prepared for school, would go into classes, participates in club activities, and has fun with her friends. But there was certainly just one extraordinary thing concerning Yuki -- she belongs to the"Brave Hero Club." What does the Brave Hero Club do? Who's the mysterious being called"Vertex?" Yuki Yuna and her friends' story occurs in Year 300, Era of the Gods.