An hour outside Tokyo, and we were in Hell, which is a thrilling place to be if you&rsquore only visiting. Owakudani (its less startling name) steams and bubbles with sulphurous hot water so intense that nothing can live there.
 But it boils eggs really well the sulphur-blackened eggs are an earnest tradition among the onsen (hot spring)-loving Japanese. &ldquoEat one, gain seven years. Eat two, get fourteen. But eat three, and live till you die,&rdquo I was told.
 A friend ate five but has lived to report the fact that the devil&rsquos food tastes &ldquojust like normal boiled eggs&rdquo. ¥ 500 for six.
