Sentou Yousei Shoujo Tasukete! Mave-chan

Rei's visit to an anime convention takes an unexpected turn when she is mysteriously transported to a fantastical world. This new reality is a manifestation of the collective desires of the convention attendees, a place shaped by their shared passions and imaginations. However, Rei finds herself trapped, with no clear path back to her own world. As the convention draws to a close, the very fabric of this fan-created realm begins to unravel. The impending end of the convention threatens to destroy the world Rei is now a part of, forcing her to confront the consequences of the fans' collective creation and search for a way to survive the impending collapse.