I was a little nervous when we went to pick up my son, who was returning from an extended stay in the Japanese countryside. He's 13, an age when kids go through tremendous physical and emotional changes. There have been days when he was a different person at dinner than he was at breakfast. And when he left, he was in one of those adolescent moods that seemed to say he'd rather be anywhere than with his family. What would he be like after two weeks away?

When he came through the ticket wicket at Tokyo Station, he was at least 3 cm taller. Everything on him smelled of mildew -- there had been record rainfalls where he was staying. But something else was different about him, too. As I tried to figure out what it was, I asked him about the highlights of his trip.

"Chopping wood with an ax," he said enthusiastically. "And whacking weeds with a scythe, and shooting thumbtacks into a log with a slingshot!" Do you detect a theme there? I did: "Fun with Sharp and Perilous Objects." When I pointed this out, my son regaled me with more tales of danger.