Muchuu no Tou

Four suns once blessed the world, and when one of them disappeared, the people mourned. Nia, an explorer of the skies, set off with her automaton companion Mano to investigate the misty tower where that sun was said to have fallen. A storm caught them en route, and their airship was damaged. They resolved to repair the vessel within the tower while they carried on searching for the missing sun. "Now then, let us begin the investigation at once!" Yet the tower's interior proved to be an abnormal space, a tangled labyrinth overrun with monsters. Ghosts also manifested, and Nia was taken captive. Mary, the one who commands the ghosts, is somewhat easygoing in manner, but it appears she will never permit intruders within the tower...