Early last year, big bets started to go wrong for a Japanese giant of toilets and faucets.

Founded in a five-firm merger, fattened by a spree of global acquisitions, Lixil Group Corp. was suddenly rocked by a Chinese accounting scandal. After a ¥66.2 billion writedown, Lixil turned to an outsider from the world of startups to lead the turnaround. And so Kinya Seto took over a more than 80,000-employee firm.

As the 56-year-old entrepreneur tells it, he has Japanese labor law to thank for his new job. In a country where it's hard to reduce staff, the best solution to a bloated workforce may be to generate more work.