Aria and the Secret of the Labyrinth

Aria is a maid tasked with cleaning the dusty basement of the mansion where she works. Behind one of the walls, she discovers a hidden room that was never on any floor plan. She enters with the hope of finding something valuable — and immediately encounters a mysterious intruder who vanishes before she can understand what she saw. The next moment, she is somewhere else entirely: an unfamiliar and ominous city with no obvious connection to the mansion she was just standing in. Finding a way back means finding a way out first.