When the law was passed to depose the previous Tennō (allow him to abdicate), an appendix was added requiring the government to look, as a matter of urgency, into the problem of the Imperial succession — the problem being that there is only one male member of the Imperial family under the age of fifty, and the law limits succession to men in the male line.
The plan was to start looking into this when all the rituals associated with the succession had finished, but they got pushed back a bit by the pandemic. However, they did finish, and the government assembled an expert committee to look into the question and make recommendations. The committee, in turn, heard from another twenty one experts, and will take their views into account.
I haven’t noticed any discussion of this in the mainstream media (although I haven’t looked very hard), but Jinja Shinpō has carried full summaries of every meeting of the committee.
This has been interesting. There has been a noticeable conservative bias to the submissions and discussions, which I suspect may be attributable to the fact that, fundamentally, only conservatives really care about the issue. For example, almost everyone (there were some exceptions) was opposed to female-line Tennō, and many people were opposed to female Tennō, although nothing like as many. There was a strong consensus against changing the currently established order of succession, even among people who thought that female-line Tennō should be accepted later, which is fair enough.
Quite a lot of people were in favour of the idea of adopting men in the male line of the old “miyakë”, parts of the Imperial family that were turned into commoners at the end of the Second World War, on the orders of the occupying Americans. They were proposing this in order to preserve the traditions of the Imperial line, which female-line succession would not.
Now, it is certainly true that female-line succession is not part of the tradition. However, the old miyakë are descended from a Tennō who reigned in the fourteenth century, and the men who are realistic candidates for adoption are at least second-generation commoners (that is, their fathers were born outside the Imperial family, as were they). There is no precedent for that, either. (And it is not at all clear to me that this would count as “hereditary” within the meaning of the constitution — I would expect a legal challenge.)
With all this argument over tradition, no-one has suggested a solution that is very clearly traditional, and has huge amounts of precedent, including some from after the Meiji Revolution. That is: get concubines for the male members of the Imperial family, and set them to work on producing more male-line males. This has not been raised because someone did suggest it when this problem was last discussed, about fifteen years ago, and drew widespread condemnation.
That means that even the conservative side of the argument accepts that it is not possible to preserve tradition in the most obvious way, because contemporary society would not accept it.
(Incidentally, while the women would have to agree, the members of the Imperial family do not get a choice; it is well-established Japanese law that they do not have the full set of fundamental human rights. That point did come up several times in the committee meetings. Someone being adopted into the Imperial family would have to agree to give up his human rights as part of the deal. It occurs to me to wonder whether the conservatives have checked whether any of the “qualified” men would actually agree if asked.)
There have been a couple of other points raised that are interesting from a Shinto perspective. First, at least two of the experts testifying to the committee pointed out that the Tennō is descended from Susano’o as well as from Amaterasu Ōmikami, and thus is in the male line (from Izanagi, presumably). The Shinto establishment would not much care for that, I suspect.
The other is that one of the women testifying to the committee, who opposed female-line succession, is from a family that claims descent from Wakë-no-Kiyomaro, who was sent to get a divine oracle from Hachiman the last time there was a suggestion of changing the imperial dynasty (in the eighth century) and came back with an answer saying “no”. Good to see people keeping up their family traditions.