A forest spirit that is only visible to children. They are associated with Camphor trees and have the ability to play the ocarina. They hang around with Catbus.
Sean: Wanna invite one of your neighbors to our BBQ party tomorrow?
John: Sure. Can I invite the karen next door?
Sean: Please don't. Try to bring a totoro.
The movie "My Neighbor Totoro" is an amorphous blob of suck. It's lack of direction and random BS will only appeal to small children or wapanese dorks.