The tightest labor market in decades is showing signs of reversing a long shift toward the hiring of temporary workers.

The number of full-time permanent workers in Japan is rising for the first time since the global financial crisis, outpacing growth in temporary jobs over the past two years.

"The labor shortage has become so bad that companies can't fill openings only with part-timers," said Junko Sakuyama, a Tokyo-based senior economist at Dai-ichi Life Research Institute.