Naia, a sky explorer, crash-lands her airship inside the mysterious tower “Shrouded in Mist” with her automaton companion Mano while investigating the vanished sun. Stranded in a magic-warped tower where rooms shift and miasma threatens to corrupt Naia within ten days, the two must split up — Naia explores while Mano guards their damaged ship. During her exploration, Naia is assaulted by intangible ghost-like spirits and encounters Mary, an undead resident who can communicate with them, from whom Naia forcibly extracts the name “Eisu” as the tower’s master by turning the spirits against her. Returning to base, Naia discovers that Mano can read the ancient books she salvaged, offering their first real clue about the tower’s secrets.