Maybe some of your visitors can help me place a Japanese folktale, that I vaguely remember. I'm really a total newcomer to Japanese culture and haven't read much more than Lafcadio Hearn, A.B. Mitford, Yei Theodora Ozaki, The Pillow Book, and the first few chapters of The Tale of Genji, so it should be in one of these books, and I've got them at hand as well, but I still can't find the story. Apparently I must have read it somewhere else after all.
Here is what I remember: Once upon a time there was a cruel tyrant who expelled old people from his kingdom. So a pious son hid his parents in his cellar. For some reason [the emperor of China?] came up with three riddles that the cruel tyrant managed to solve with the help of that son. The first riddle was about the right position of a piece of wood, and was solved by throwing it into flowing water. The second one had something to do with snakes, I think. The third one consisted in drawing a piece of string through a weirdly shaped stone. He solved the problem with the help of some small animals, maybe ants. (Like Daedalus with the snail shell.) Having suceeded, the son revealed that his parents counselled him in this and the tyrant repealed his unjust law.
Now all that Google turned up was this. Evidently a variant to the tale I remember, but two of the three problems differ, and Yasushi Inoue frustratingly just says that they were solved, but not how. Do you remember my story or at least a more detailed version of the other one? (Or if there's a better place to ask this question, could you please direct me there?)
Thanks in advance!