Zashiki warashi is one of the sweeter, less malicious youkai. Often portrayed as a small ghost child (usually a girl), the zashiki warashi brings good fortune to those that inhabit the home they haunt. The name originates from the kanji zashiki for tatami room, and an older word for child, warashi.
This young ghost child, usually around 6 or 7 years old, likes to play pranks and be very mischievous. Their tricks include pulling out a pillow from underneath a sleeping person, placing cold hands on their face to surprise them, or sometimes even sleeping on top of them (which is perhaps a bit scary but somewhat sweet in my opinion). All of their pranks are harmless, and purely childish.
As I said earlier, if a zashiki warashi occupies your home, it brings good fortune and prosperity. So many encourage the zashiki warashi to stay. Because if they were to leave, you would have nothing but bad luck (~_~;) So in order for them to stay, you have to first of all notice their presence, and then care for the ghost. After all, it is but a child who seeks and craves attention, perhaps even love.
A few inns in Japan, more specifically the iwate prefecture have residing zashiki warashi, and many customers travel to stay over and hopefully bring themselves good luck. I don’t know if I would have the courage to sleep in such an inn, but what an interesting thing to try!