Red Key

Rika wakes up dead, then opens her eyes in another world with a magic pin on her robe and a strange power that lets her rewind a few seconds at a brutal cost. She grabs the only work she knows, dungeon master duty, and turns that skill into a way to keep paying adventurers alive when a real wild dungeon starts warping the magical academy. Her first useful tool is not a sword. It is her habit of spotting bad exits, trapped floors, and lies in people’s voices. Airi keeps appearing at the edge of her missions, and Rika keeps telling herself that is the reason her pulse keeps racing. Then old names, broken records, and one hidden notebook start pointing to the same night ten years ago.