While people fret about robots taking human jobs, machines in Japan are stepping in to fill vacancies amid the worst labor shortage in more than 40 years. That is creating an opportunity for up-and-coming startups focused on automating warehouse tasks.

Nitori Holdings Co., the nation's biggest furniture maker, last week deployed 79 robots to move around shelves filled with products at its Osaka distribution center. The company, which introduced the country's first automated furniture warehouse in 1980, is looking to reduce its reliance on human labor.

Japan's shrinking pool of workers helped push the number of jobs for every applicant to a ratio of 1.55 in October, the highest since 1973, according to the labor ministry. While companies such as Amazon.com Inc. have been investing in warehouse automation for years, many Japanese logistics providers are now scrambling to catch up. To keep up with booming orders from e-commerce companies and customers expecting fast delivery, businesses in the country are turning to startups such as Ground Inc. and Acca International Co.