When Yuriko Koike was Japan’s environment minister in 2005, she was hailed by legions of salarymen as they shed ties and jackets in summer during the “Cool Biz” national energy-saving campaign that she helped to launch. Now, as Tokyo governor, Koike has taken the idea a step further: shorts in the office. In April, the Tokyo Metropolitan Government said it would allow male employees to turn up for work in shorts, and it urged businesses across the capital to adopt similarly relaxed dress...