The Multiverse boundary keeper is a highschool student

The story follows Anne, an awkward, introverted high school student who is suddenly thrust into an extraordinary role as the keeper of the multiverse. After feeling disconnected from her classmates and only having one close friend, Sofia, Anne's life takes a dramatic turn when she discovers a magical box in her school's library. Inside, she finds Leotromedius, a small, talking chimera, who informs her that she has been chosen to maintain the balance between reality and different universes.