Here is a video news report regarding Their Imperial Highnesses Crown Prince Naruhito and Crown Princess Masako of Japan. Apparently, Their Imperial Highnesses were invited to the upcoming inauguration/investiture of His Royal Highness Prince Willem-Alexander of Oranje on April 30, 2013 in the Netherlands.
Unfortunately, a decision has yet to be made. Nevertheless, I do believe Crown Prince Naruhito will attend though Crown Princess Masako will not. The Imperial Household Agency (IHA) will no doubt claim that she is still to ill to travel outside of the palace or her room for that matter. Poor woman.