Clashes between Japanese students and police have long had the ritual quality of a classic No play. First would come the students, helmeted and frequently masked with towels. From under a forest of red banners, they would let go a barrage of stones for a salutation. The police, brandishing nightsticks, would retaliate with exploding tear-gas charges. Even in the most impassioned confrontations, however, the actors on both sides rigidly adhered to an unwritten law: no killing.
Last week, in the bloodiest of a long series of skirmishes over the building of Tokyo's new jetport at Narita, some 40 miles southeast...