An hour outside Tokyo, and we were in Hell, which is a thrilling place to be if you’re 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. “Eat one egg, add seven years to your life. Eat two, get 14. But eat three, and you live till you die,” said our guide. A colleague ate five but has lived to report the fact that the devil’s food tastes “just like normal boiled eggs”. Y500 for six eggs.