Workers born outside Japan are playing an increasingly important role in the world's third-largest economy. Just don't call it immigration.

The country is often said to pride itself on homogeneity and an aversion to outsiders. But as Japan's population declines and ages, employers are becoming aware of their constraints. The number of employees from overseas has more than doubled since 2012 to about 1.5 million, says Bank of America Merrill Lynch.

In recent conversations with local business owners, few expressed qualms about adding more of the foreign-born workers to their payrolls. With the jobless rate at a microscopic 2.2 percent — and two jobs for every applicant in the Tokyo area — pragmatism is starting to kick in. And while robots and automation are a part of the answer, that doesn't solve everything. Labor must be imported.