Nonlife insurer Sompo Japan Nipponkoa Holdings Inc. plans to acquire nursing home operator Message Co., company officials said Friday, as part of efforts to diversify its sources of revenue in a market being squeezed by population decline.

Sompo Japan plans to boost its stake in the nursing care provider to more than 51 percent from the current 3.5 percent, making it a subsidiary, the officials said.

Combined with the elderly nursing care unit of pub and restaurant chain operator Watami Co., which Sompo Japan earlier said it will acquire for ¥21 billion, the move will make it the country's second-largest player in the nursing care business, following Nichii Gakkan Co.

Message, based in Okayama Prefecture, is Japan's third-largest nursing care company and logged sales of ¥78.9 billion in fiscal 2014 through March. It operates over 180 nursing homes for the elderly nationwide under various brands including Amille.

Message has been troubled by cases of abuse and fatal falls at its nursing homes, prompting president Toshio Sato to resign.

Sompo Japan aims to rehabilitate Message and improve its compliance following the acquisition, the officials said.