Mamizou Futatsuiwa is a youkai tanuki who originally lived outside Gensokyo. She moved to Gensokyo to help a friend.
She originally lived with humans in a city named Sado. Mamizou often lended them money and got along with them well. However, she doesn't get along with foxes and there are no foxes in Sado.
She currently lives in Myouren Temple, along with Nue Houjuu.
She holds the power to disguise herself and objects by shape-shifting. Source: Touhou Wikia
She makes an appearance in the 9th chapter of Touhou Ibarakasen ~ Wild and Horned Hermit