For the Japanese to wheel out their Emperor to make a televised address yesterday on the nuclear crisis is virtually unprecedented. To produce the country's most sacred figurehead in this way and to risk involving him in a situation which could become deeply political shows just how concerned the government and establishment has become not just over the dangers of a nuclear meltdown but also of public reaction to it.

Indeed there is only one proper precedent for this act, which is when Emperor Akihito's father, the Emperor Hirohito, appeared on radio on August 1945 to make the dramatic and painful announcement of his country's surrender to the Allies, despite all the promises and preparations to fight to the last man. For many Japanese, virtually all in fact, this was the first time that they had heard the "divine" figure speak at all.

Once produced for that purpose, the Emperor and his successors were put back behind closed doors, stripped of their divine status and progressively stripped of all authority save that of a constitutional monarch with far fewer powers than the British Royal Family.

That was partly a decision by the Japanese post-war establishment in a careful attempt to shield the man who was still regarded as the embodiment of his country from becoming the defendant in a war crimes trial which many outside believed he deserved. But it was also a deliberate decision by the US occupying forces to put him on the margins as a useful token of continuity in their plan to democratise and modernise Japan and remove the vestiges of traditional obedience and hierarchy.

If this was the aim, it has turned out to be a generally effective compromise between local sensitivities and the pressure of progress. Of course there is still the old vestiges of godhead in the description of the emperor as tenno, or "heavenly sovereign", and a glamour, which excites foreigners more than the Japanese themselves, attached to the world's oldest surviving monarchy.

The reality has become more mundane. The Emperor has continued be regarded as a symbol of national unity, but among younger generations he and his family have become pretty marginal to their lives or thoughts.

There have been very tentative efforts by the Imperial Household to let a little humanity in. The Emperor Akihito himself and Crown Prince Naruhito are genuinely modest in character and behaviour. Both have married commoners, and both follow their own interests (Akihito, like his father, is a biologist).

But efforts to popularise the family in the manner of the UK royals have, as with the British Royal Family, stumbled on problems with the daughter-in-law – in this case Crown Princess Masako's growing unhappiness with her confinement in the palace and the pressure on her to produce a male heir (they have a daughter).

Even here, moves to modernise the monarchy by necessity and alter the law to allow female succession were quickly withdrawn when Naruhito's younger brother produced a male child, thus providing a third in line of succession. That does not seem to have saved the Crown Princess from serious depression, which her husband, who studied in Oxford, painfully acknowledged not in Japan but on a trip to Spain. The general impression left has been (not unlike our own dear royals) of a less than happy family run by a depressingly claustrophobic and traditionalist court.

The danger of bringing the Emperor centre-stage now is that the very act, far from inducing calm, may actually increase the sense of foreboding. It also risks politicising the Crown at a moment when events are still open-ended and their consequences on public mood are still uncertain.

Had the Emperor's address confined itself to expressing sympathy with the victims of this natural disaster and solidarity with the people of his country in their hour of grief, it might have seemed decent if uncontroversial. But it is impossible now to talk of the catastrophe without mentioning the crisis at the Fukushima Daiichi plant. And that in itself is comment on just how finely balanced the situation is today in Japan.