A labor reform law came into force on Monday, setting a legal cap on long work hours to change Japan's notorious overwork culture blamed for causing sickness and deaths.

The cap, which only targets major companies for now, is one of the three pillars of labor reform pushed by Prime Minister Shinzo Abe, who faces the difficult task of addressing Japan's shortage of workers that has now become a major issue across various industry sectors.

The law limits overtime work to 45 hours a month and 360 hours a year in principle. The monthly cap can be extended in busy periods, for up to six months a year.