Fate/Labyrinth

Manaka Sajyou, a mysterious figure with a unique connection to the fundamental nature of reality, seeks to experience something beyond her current existence. Driven by a desire to understand concepts like change and dreams, she embarks on an extraordinary journey through dimensions beyond normal comprehension. Her consciousness travels to a strange realm where a special variant of the Holy Grail War unfolds - a labyrinthine battleground where four pairs of Masters and Servants compete in an unusual ritual. In this unfamiliar world, Manaka finds herself connected to a particular Master-Servant pair, establishing a peculiar bond with both the summoner and the legendary female King Arthur who serves as their Servant. As she navigates this mysterious war, Manaka must grapple with her own nature while witnessing the complex dynamics between the participants of this unprecedented conflict. (Source: Type-Moon Wikia)