In a quest to reduce their reliance on one of the world’s least profitable banking markets, Japanese lenders are setting their sights on a much more lucrative one: Mexico.

Mitsubishi UFJ Financial Group Inc. and Mizuho Financial Group Inc. are among so-called megabanks expanding in Mexico, riding the coattails of Japanese automakers that are building factories there to serve the U.S. market.

MUFG, as Japan’s biggest bank is known, plans to open an office in March in the central Mexican city of Leon to service the nearby factories of automakers including Nissan Motor Co. and Honda Motor Co. Mizuho is seeking to increase the number of employees in the country fivefold as it opens its first banking subsidiary there as soon as September.

Japan’s megabanks have been boosting lending overseas to earn higher margins than at home, where the central bank’s recent introduction of negative interest rates threatens to make loans even less profitable. While much of the expansion has been in Asia, slowing growth in China is damping economies throughout the region, giving impetus for lenders to focus on countries such as Mexico, a market Japanese companies are entering in droves.

“Motor vehicle production in Mexico is booming,” Ryoichi Konishi, deputy general manager of MUFG’s Mexican unit, said in an interview. “We expect growth to continue.”

Economists project Mexico’s economy will grow 2.6 percent in 2016, a third straight year of expansion. Its inexpensive labor and close proximity to the U.S. have prompted Japan’s automakers to boost output in the country of about 122 million people. Production reached a record 3.22 million vehicles in 2014, over 80 percent of which are exported, mainly to North America.

“Banks being able to piggyback on a certain industry that’s setting up factories and expanding in an overseas market is one very good way for them to go in,” said Takashi Miura, a Tokyo-based analyst at Credit Suisse Group AG. “There’s going to be a high degree of safety and they can also expect a certain volume of business.”

Konishi said MUFG has doubled customers in Mexico to about 600 Japanese and 50 non-Japanese companies in the past three years. Loans have grown about 2.7 times to $4 billion in the three years to September. That makes Mexico similar in size to MUFG’s business in Asian markets like Malaysia and South Korea, where balances fell slightly year-on-year to $5.4 billion and $3.6 billion, respectively.

Just under 40 percent of MUFG’s ¥112 trillion loan portfolio as of September was from overseas. Lending abroad grew about 50 percent over the past three years, compared with about 6 percent for corporate loans at home.

The Tokyo-based bank will deploy six employees to the Leon office, which will be the second overseen by its local arm. MUFG has 140 workers in Mexico City, where it has provided full banking services including deposits and remittances for 21 years.

Mizuho, Japan’s third-biggest lender by market value, received approval last year from Mexican regulators to open a full-service banking subsidiary. The new unit will boost personnel to 50 from the 10 at its existing representative office, according to Hiroto Oshinomi, a senior manager in the international coordination division.

“As well as meeting the financing needs of our customers, we aim to help companies expanding business there and earn noninterest income from remittances and deposits,” Oshinomi said.

The average net interest margin — a measure of loan profitability — at four publicly traded Mexican banks is about 5 percent, higher than most markets tracked by Bloomberg. That compares with less than 1 percent for Japan’s three largest lenders, data compiled by Bloomberg show.

According to Mizuho research, the number of Japanese companies operating in Mexico more than doubled to 814 in 2014 from 350 three years earlier.

Aisin Seiki Co., a vehicle parts maker, plans to start production of sunroofs and door handles at a new factory in Mexico in 2018. The plant will supply components to Toyota Motor Corp. and other automakers including General Motors Co. and projects sales of $50 million by March 2021.

Sumitomo Mitsui Financial Group Inc. is expanding more modestly in the Latin American nation than its peers. Japan’s second-largest lender by market value established a finance company in March 2015 that specializes in local-currency lending. Its four employees provide loans in Mexican pesos for project-finance deals as well as Japanese automakers and parts suppliers.

Kazuya Ikeda, head of strategic planning at Sumitomo Mitsui’s international banking unit, said the structure is more efficient and enables greater flexibility to cooperate with its branch in New York than a full banking unit would.