The Crown Prince's paternity could also be a myth, yet we believe that his father is The Emperor. If we believe that he is The Emperor's son, then we have to believe that he is a male line descendant of the first emperor, because both informations come from the same source - the Imperial Palace. Choosing to believe one statement, but not the other one, would be hypocritical. Besides, many scholars (including Robert John Smith who published his book in 1974 and Hugh Byas who published his book in 2007) take this "myth" very seriously.
Anyway, it was common for a childless ruler to adopt a male-line nephew or another male-line relative. Such a child would usually succeed even without adoption. Adoption was used to make the succession smoother, as a civil war could break out after the death of a childless ruler.
I have to stress this once again: I do not oppose female succession to any throne, but I do oppose female-line succession to the throne of Japan.
You say - if I understand you right - that if one disbelieves one thing a person or institution is saying one ought to disbelieve in consequence all the rest of what they say. In this point, I do not share your opinion. I suppose the IHA to be capable of telling whatever lie they deem necessary to “preserve face” but that does not mean that I think them incapable of occasionally also saying the truth when it fits their concepts. I believe Naruhito to be the son of Akihito because, at present, there is no suspicious fact within my knowledge that would indicate the contrary. But if there WERE such suspicious facts the statements of the IHA would certainly not prevent me from taking them into serious consideration. Anyway, there are already, at least, two things that the IHA says and that, to my mind, are lies (for reasons that I have explained somewhere else in this forum): the “natural” conception of Aiko as well as that of Hisahito. So, I really do not see what should prevent me from disbelieving even more of what they say.
That does not mean that I am absolutely sure that the famous line of descent HAS in fact been broken. The scientist whom Fritz and Kobayashi quote (who, bye the bye, seems to say that the line of descent WAS broken by the adoption which, if he is right, excludes the possibility of adoption within the family in this special case) may be wrong, or even more probable, he may have some or even strong evidence for what he says – but after so many centuries having passed I doubt that he could be able to prove what he says with a certainty that would not allow of a single doubt. We know that it is rather common in the science of history that you may have a certain or even strong evidence for what you say but after much time having passed and, even worse, if it has possibly been tried to cover up a certain fact, a strong probability is usually all you can reasonably hope for. So, the line of descent may have rested unbroken for a very long time, or it may have been broken. All I am saying is that we cannot be absolutely sure of neither one possibility nor the other.
And concerning the practical consequence of this question, the succession: although I do think that there would have been a certain chance for the Japanese nation in a woman inheriting the throne, a chance to heal the gap between - let´s say: the more modern or Western-oriented Japanese (who usually belong to the younger generation) on one hand and the more conservative, older Japanese on the other, I clearly see that this chance was gone as soon as Hisahito was born. The wide national consent about accepting a woman as the heiress was only possible as long as there was no alternative.
And, besides that, there is, at least, one person who is much better off like things are now: Aiko´s future husband.
I am very sure that Hisahito´s future wife will have a hard life but the life of Aiko´s husband, had she been destined to become reigning empress, would probably have been hell on earth (and, mind me, not because of Aiko)… So, setting aside all ideological reflections, I think that Hisahito´s birth saved a lot of trouble to a lot of persons (well, probably not including Hisahito himself…
) The imperial family´s life is hard enough as it is, IMO, they already have probably just as much problems as they can handle (or even more).
So, my point is neither that I am absolutely sure that this unbroken line of descent is a myth nor that I insist on Aiko inheriting the throne. But what I absolutely dislike is the way in which a lot of official Japanese (well, not only Japanese but here we are talking of Japan) use or rather: abuse historical facts or – lies. I will give an example for what I mean: in January 1990, Japanese nationalists tried to kill the mayor of Nagasaki, Hitoshi Motoshima, who had publicly declared that, in his opinion, the emperor (Hirohito) had been to a degree personally responsible for the war.
But who was criticized by the public after that incident? Not the criminal who had tried to kill Motoshima and not the fanatics who had before been calling for his death - but he himself, the victim. Noburu Tasaki, director of the museum of peace in Nagasaki, put it like that: “The Japanese do not want to believe that Japan was responsible for committing cruelties. We live in harmony with other nations.” So, by saying that the emperor, the symbol of the Japanese mind and unity, was not guiltless, Motoshima had destroyed harmony. And that was his fault. If he had been right or wrong in saying that – that was not an issue and was never discussed. (For more and, IMO, even more shocking, details about nasty facts just having been denied because they were nasty not because they were untrue - in Japan and elsewhere - see: Erna Paris: “Long shadows. Truth, Lies and History.” Toronto 2000)
And this is a sort of abuse of historical science that I will always and everywhere strongly oppose. And that this is still the prevalent way of dealing with the history of the Japanese imperial family we can also see from the fact that prince Naruhito had to struggle very hard when he wanted to study history at an independent university: That was not thought suitable for a member of the imperial family because there he might be taught to take too independent a view of the tenno and the part he had played in history. - Many conservative, nationalist Japanese do not care if something is true or not, as long as it serves their purpose. They think that nationalism is more important than facts. It is this attitude that I will simply never accept.
Also because in this way we actually do not have a fair chance to find out what the facts really are. A Japanese historian who would find out during his research that the line of descent in the imperial family has in fact been broken would need nearly the courage of a Galilei to let this information slip to a broader public. Erna Paris reports that a professor of pedagogics, Saburo Ienaga, and a veteran of Nanking, Shiro Azuma, who had tried to inform the public about the Nanking massacre got anonymous threats that they would be killed. Ienaga´s house was beleaguered by angry nationalists who screamed threats, and collegues blamed him of being “unjapanese”. (Remarkably the same accuse that has sometimes been uttered against the crown princess.)
The Nanking massacre was committed on the 13th December 1937 by Japanese troops in Nanking, China, and I do not want to give any details here because they are really too horrible. (If you are interested see: Young Shi; Yin, James: The Rape of Nanking: An undeniable History in Photographs, Chicago 1996 or:
Nanking Massacre - Wikipedia, the free encyclopedia.) Although it is fairly well documented and is undoubtedly a fact, it is still widely unknown to the Japanese public. A courageous English professor in Fukuoka, on the Kyushu island, Yoshiyuki Masaki, has translated information about the Nanking massacre into Japanese and has put it on his website, asking liberal members of the Japanese house of commons, the Shugiin, for their support. A member of the government told him that he absolutely agreed with him and that, according to him, Japanese schoolbooks should mention the Nanking massacre (which they do not). But when Masaki asked him if he would allow him to put this statement on his website the government member said that he preferred his opinion not to get public. Another politician, member of the Shugiin, consented to have her support published on the website but received so much hate-mail that in the end she decided to withdraw her consent.
That people in Japan are afraid to publish controversial facts, and especially concerning the imperial family, even if they are undoubtedly true or even banalities, you can also see from the fact that the Japanese TV does not dare to broadcast a statement from a British journalist who says that the common British people are a bit at a loss to understand why it should be so unthinkable to the Japanese nation to let a woman succeed on the throne and that the Japanese interviewer asks him: “if he is not afraid of the ultra right”.
The Family And The Society: Search results for A+girl+would+be+better+for+Japan
So what I want to say is that even if there were an absolutely indubitable proof for the line of descent of the imperial family having in fact been broken I see reasons to doubt that this information would ever make its way to a broader public.