Miho Marui isn't exactly sure how she wound up standing on top of a bus on a blustery Tokyo day in 2009, staring up at the 35-story headquarters of KDDI Corp.
There she was, hands trembling, as she shouted up at her bosses through a loudspeaker while coworkers pressed against the windows to watch her pick a fight with the nation's second-largest phone company over labor practices at one of its subsidiaries.
"I guess I was just mad," she said.