The pyramid-shaped Lunar Capital facility, Asama Joue(Impurity-Cleansing) Mountain, was originally her shrine, where she was worshipped alongside Yuiman. Iwanaga had the power of perpetuity, which is the power to maintain the same shape, as long-lived as stone. The Lunarians adored that eternal power, but she refused the idea of joining their ranks. The power of perpetuity is the power of rejection. Even with her shrine being taken over, she continued to reject them until she was eventually sealed.
During the events of Fossilized Wonders, she was unsealed by Toyohime. She was ordered to freeze all of Gensokyo, in order to stop the impurity(=life information) coming from The Outside World. She agreed to cooperate with Eirin and Toyohime as part of their plans to save The Lunar Capital, and later on be defeated by the protagonists to save Gensokyo, so that Yuiman could be saved.
