Originally Posted by
Extra mats
Suiten Nikkou Amaterasu Yano Shizu Ishi.
Sweets Heroic Spirit Cas-ko’s Noble Phantasm. She doesn’t use it much.
In EXTRA it is shown as a mirror, but it is actually the Tamamo Shizuishi, a sacred regalia among sacred regalia.
The Shizuishi was enshrined in Izumo, and it is a sacred treasure said to have been brought to Earth from Heaven by Takehideri no Mikoto, and is thought to be an object of worship (shintai) of the Great Gods of Izumo.
According to the Nihon Shoki, it was taken from Izumo at the request of the Imperial court and later enshrined in Kawachi.
Perhaps it's the Yata Mirror that came afterwards, the shintai of Amaterasu Oomikami.
The Shizuishi is thought to be the prototype of Mononobe’s Ten Sacred Treasures (Tokusa no Kandakara), and is said to have the power of the Netherworld which can revitalize the soul and life force and even revive the dead.
Since this is too cheat, in the game we made it just provide unlimited magical power.
Though this is another digression, the Ookuninushi that enshrines the Tamamo Shizuishi is a being considered to be god among gods.
Despite Cas-ko's appearance, she is indeed a top rank Divine Spirit class Servant.