Hisahito´s father, uncle and grandfather had their own way when they married: Fumihito was allowed to marry before his elder brother although that is against Confucian law. And Akihito and Naruhito insisted on marrying ladies who were not to be so easily convinced.
When Michiko´s parents heard that their daughter should become the crown princess they sent her hastily to Belgium and the US. Japanese way to politely say: “Thanks but no thanks.”
One of Akihito´s friends, Masao Oda, explained that those close to him knew that the prince wanted to die if Michiko refused to marry him. And so they did all in their power to help him: Oda´s brother supported Akihito in connecting to his beloved via phone calls (difficult!!! because Michiko´s parents should not know and empress Nagako should not know either...). And one executive of the kunaicho, Michiharu Tajima, wrote in his diary: “The opinion of everybody concerned seems to be that the marriage with Michiko Shoda has to be made possible by whatever means because it is the only hope.”
And, as we all know, Naruhito in his turn needed even more time to convince his one-and-only to marry him. Everybody helped to support him and, of course, a lot of young women were presented to him one after the other but nobody tried to force him to do anything against his will - even when he was already “competing with prince Charles for the title of “eldest bachelor crown prince alive”” as Naruhito humorously expressed it.
So, if none of them had been compelled to marry against their will to ensure succession I really do not think that they will begin with it in the 21st century. (Not even in Japan…
) And even if they wanted that: WHO should force Hisahito? They can hardly let the parliament make a law that commands the heir of the throne to marry ASAP. The whole world would roar with laughter.
And in the family? When Hisahito will be grown up his uncle Naruhito will - in all probability - be emperor. And even in my wildest dreams I cannot imagine an emperor Naruhito who forces his nephew to marry in order to guarantee male succession…
Considering his own story, I think we can fairly declare that to be absolutely out of the question. I think in such a case he would not try to solve the problem by making his nephew unhappy but by trying to use all of his influence to find a way to include women in the succession – if even only as “spares” if Hisahito should die without having a son. If Hisahito had never been born the Japanese would have surrendered to necessity anyway and would have changed the law. If the problem comes up again because Hisahito is unwilling to marry or does not find a bride this will also be a sort of necessity, and why should the Japanese then refuse to face reality? As already somebody somewhere said: if Hisahito should only have daughters his eldest will probably become reigning empress without much further ado. And most of us will probably not live to see her reigning anyway…