Streak of Luck

If you see a naked man walking down the street, your first instinct might be to flee. But for thousands of men in central Japan each winter, there's only one acceptable response: strip down to almost nothing and go chase him. That's the way it has been done in the city of Inazawa for centuries. The event is perhaps the most famous of several hadaka matsuri , or "naked festivals," held around Japan annually.

The festivals are based on traditional Shinto purification rituals. In Inazawa, where this year's event will be held on March 2, one self-confident fellow is...