This little book from 1969 is a standard for Japanese kids, in the same way that "Little Golden Books" or Dr. Seuss are in America. I think part of the appeal is the unique artwork, which is composed of cut patterned "washi" paper. The effect is similar to what South Park used to look like, before it got all computerized. Here's an example:
So here would be a good place for me to tell you the theme of the book.
That picture above is of a robber, running off into the night with a bag full of stolen goodies. The book describes all the things which are up at night, when little children are sleeping... or when they should be sleeping.
The title of the book "Nenai-ko dare da" contains an invented word that roughly translates to "Little No-sleepers". That would be children who don't sleep when they are put to bed. Naturally, robbers are just one of the hazards laying in wait for little no-sleepers.
Much more menacing are ghosts.
If ghosts catch little no-sleepers, they turn the children into ghosts, and kidnap them, taking them to the spirit world, never to see their parents again!
That kid had feet in all the other pictures.
Damn! I don't even want to know what happens to kids in Japan who don't eat their vegetables.
My wife loves this book (our copy has some of her childhood scribbling in it, which is cool), but she says it also freaked her out a bit when she was little.
I asked her, "Don't you think this is too terrifying to show a very young kid?"
She replied, "Well at least we don't show our children The Wizard of Oz here, with those flying monkeys."
I could ask her more about it, but she's in bed right now, fast asleep.