Pepper, a humanoid robot developed by SoftBank Group Corp., moves around on its own to guide passengers at sushi shop in Tokyo, Japan.

When Tetsuya Sawanobori finished grad school about a decade ago, he decided to start his own business. He set up a restaurant in Japan, following in the footsteps of his grandparents and uncle.

A year later, he stopped.

"I realized it's very hard," Sawanobori told CNBC. With few holidays, and working on average 16 hours a day, he said he was "exhausted, and that's why I gave it up."

"Right now, especially in the food service industry, they have a serious lack of labor because people tend to avoid these kinds of jobs, doing daily, repetitive" tasks, he said. "It's very hard and overwhelming for people ... they usually work very long, like 12 hours, or some people work 15 hours a day."

He explained that the situation is becoming more severe as Japan's population continues to shrink, putting more pressure on active workers.

Long office hours, often seen as a measure of hard work, have become a cultural norm in post-war Japan, where decades of economic growth led to the country's emergence as the world's third-largest economy. Starting in the 1990s, that growth slowed — but the long hours remained. The problem of "overwork" is serious enough that Japan's business community and the government are working to address the issue.

Prime Minister Shinzo Abe has called for the government to examine plans to hire more skilled foreigners; meanwhile, many industries are turning to robots as a way around the labor shortfall.