Ko Sasaki/New York Times/Redux To be a Japanese politician is to spend your career exercising restraint. There's the somber suit, the gray demeanor, the vague words that defy position taking. But as radiation wafted from the earthquake- and tsunami-damaged Fukushima Daiichi nuclear power plant toward the city of Minami Soma, some 15 miles (25 km) away, Mayor Katsunobu Sakurai, 55, abandoned the us