Mahou Shoujo Lyrical Nanoha INNOCENT

A world exists alongside other storylines where, in the summer of 2010, a researcher from a small city creates a virtual reality game called "Brave Duel." The game uses motion-sensing technology for team-based card battles and becomes a global phenomenon. A girl becomes involved in this phenomenon, encountering various opponents and developing through their interactions and competitions. The events of this summer mark the beginning of her journey.