Foreshadowing in "Urashima Taro and the Princess of the Sea"

An example of foreshadowing is when the princess tells Urashima, "There is just one thing about that box," and "you must never, never open it if you wish to return to the Palace of the Sea." The author is

foreshadowing that something very bad will happen if Urashima opens box he was given by the princess. If he gets tempted by the box or forgets about his promise and opens the box then he can never go back to the palace.