The azure key is a key found within the town of Gongdung after completing the Goshima section of Curse of the Black Stone and revisiting the island and can be found in the eastern trunk north of the building in the north-east of the town.
It unlocks a door in the first room of the Temple of Aminishi, just before the final barrier, leading to a new area, the azure room. The door can be unlocked in story mode. The key must be used on the door to unlock it.
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