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 chosen to be the official streaker. He's shaved and then marched through the Kounomiya Shrine, where a throng of around 9,000 men wearing only loincloths attempt to lay their hands on him as thousands of spectators watch. The naked man is supposed to collect the bad luck and impurities of all who touch him. The crowd can get overly enthusiastic (sake is involved), so the man is protected by guardsbut he still ends up pummeled and bruised by the conclusion of the festival. Then he ritually transfers the amassed bad luck to piles of glutinous rice balls for safe burial, dons his clothes and leaves. As for the half-naked throng outside, their luck improves right awaythey get to change out of their loincloths.
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.