For the modeling agencies of Chiba city the next few days will be mayhem. They have less than a week to recruit the biggest, prettiest army they have ever sent into battle. And without enough gorgeous women to save it from disaster, the 2009 Tokyo Motor Show may mark the beginning of Japan’s long descent to irrelevance.

The young ladies of Chiba have for many years been a sensitive barometer of industrial confidence and the wider Japanese economy. Their city sits on the doorstep of Makuhari Messe — the giant expo centre on the outskirts of Tokyo that hosts the country’s biggest trade fairs. When Japanese companies have something to tout to the world, the marketing tradition of Makuhari is to peddle it with beauty. The less attention-grabbing the product, runs the chauvinist trade-fair logic, the prettier the girls needed to front the display.

In years where Japanese companies have produced dazzling new electronics or earth-shattering advances in nanotechnology, the girl-count has thinned out. When innovation fails, sex is hauled in to bolster interest. And the phenomenon is especially acute with the biennial Tokyo Motor Show. In the year that Nissan proudly unveiled its Skyline GTR, it knew that the product itself would elicit appreciative drool and required draping with only a couple of so-so models. In the same year – a year in which there had been very few significant advances in tyre or brake technology – Akebono and Falken shipped in platoons of the very loveliest Chiba had to offer.

But while in the past individual companies may have been nervous, in 2009 the entire Tokyo Motor Show is in peril. An institution that has never needed to overstate its importance, its relevance or its sexiness has suddenly realised that it is running desperately short of all three. Certainly the local biggies — Toyota, Nissan and Honda — will do their best to inject some engineering spice with something green and electric, but even now, with the show opening next Wednesday, there is none of the excitement that used to surround the event.

There are three huge mood dampeners that the Chiba girls must face. First, there is the problem of the signal non-attendance of overseas carmakers who once jostled to be in Makuhari. With many global brands pulling out altogether the whole show will be slightly less than half the size it was in 2007.

Second, there is the miserable lack of novelty. At previous shows, about 40 new cars have made their world debut at the Tokyo Show; this year the premiere tally will be 19.

Finally there is the widely known fact that the Japan Auto Manufacturers’ Association talked quite recently about scrapping the show altogether.

If even the Chiba girls are unable to seduce victory from the jaws of defeat, the 2009 Tokyo Motor Show will send two very clear messages about Japan. The first is that China has properly overtaken Japan as the pre-eminent Asian economy. Nobody felt they could afford not to be at the Shanghai auto show. Tokyo must give those automakers reasons to regret not being there this year, and if it does not, the event may permanently slip off the radar.

Furthermore, a lacklustre motor show will go some way to confirming that Japanese consumers themselves are less splashy with their yen than they used to be and are no longer worth bothering with. Versace, French Connection and a variety of other brands have already made that decision, and the approach may rapidly migrate from the clothes industry to larger products.

If the Japanese are not interested in cars — and that is the clear implication of the no-shows by foreign manufacturers — then many will start re-evaluating the old view that Japanese customers were the most reliable in the world.

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