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{4}{p/w} Depending on Yokai you choose.
The Book of Yokai (One-arm). If you can decipher its true name twice, sacrifice 10 symbols, and pick 5 numbers while using an RNG between 1 and 20, you will achieve this mythic card. It allows you to make a deal with either Shuten Doji, Tamamo No Mae, Emperor Sutoku, or a horde of various Yokai (reference rules for more detail). You may also keep this card as a Relic and more (reference rules).