In Japanese folklore, the Nyoijizai is a spirit that has the ability to scratch that itchy spot on your back which you can't just seem to reach, no matter how hard you try. Its name, Nyoijizai, is a pun meaning both “free staff” and “exactly as you please.”
Nyoijizai is a kind of priest’s staff (a bit like a wizard staff) that has turned into a yokai (or supernatural monster) after serving its master (the priest) for many many years.
It bears a very strong resemblance to a mago-no-te, a backscratcher. So, as an animated spirit its only power is its ability to scratch that itchy spot on your back which you just can’t seem to reach.
-Foster, M.D., 2009. Pandemonium and Parade: Japanese Monsters and the Culture of Yokai. Univ of California Press.