ONCE YOU GET past the overall irony of the situation, you realize that killing a guy in the middle of his own health club has a lot to recommend it.

The target was a yakuza, an iron freak named Ishihara who worked out every day in a gym he owned in Roppongi, one of Tokyo ’s entertainment districts. Tatsu had told me the hit had to look like natural causes, like they always do, so I was glad to be working in a venue where it was far from unthinkable that someone might keel over from a fatal aneurysm induced by exertion, or suffer an unlucky fall onto a steel bar, or undergo some other tragic mishap while using one of the complicated exercise machines.

One of these eventualities might even be immortalized in the warnings corporate lawyers would insist on placing on the next generation of exercise equipment, to notify the public of yet another unnatural use for which the machine was not intended and for which the manufacturer would have to remain blameless. Over the years, my work has made me the anonymous recipient of at least two such legal encomia-one on a bridge traversing the polluted waters of the Sumida River, in which a certain politician drowned in 1982 (“Warning-Do Not Climb On These Bars”); another, a decade later, following the aquatic electrocution of an unusually diligent banker, on the packaging of hair dryers (“Warning-Do Not Use While Bathing”).