Japanese buyout firm Unison Capital is seeking a buyer for its popular sushi restaurant chain Akindo Sushiro, in a transaction that could be worth as much as 70 billion yen ($893 million) and mark one of the largest private equity sales in the country in recent years, two sources said.

Unison, Japan's second-largest private equity firm, has hired Mitsubishi UFJ Morgan Stanley as an adviser for an auction, said the sources, who had knowledge of the sale but asked not to be identified as the information is not public.

Unison bought Akindo Sushiro, which runs automatic sushi restaurants nationwide, in 2007.

The company's revenue has grown 69 percent since then. It posted 99.8 billion yen in sales for the year ended September 2011, compared with 59 billion yen for the year to September 2007, according to its web site.

Net profit fell to 979 million yen for 2011 from 1.1 billion yen in 2007.

A Unison spokeswoman declined to comment.

Unison has been one of the most active private equity funds recently. Last month it agreed to buy drug maker Showa Yakuhin Kako, in its third buyout in six months. ($1 = 78.4150 Japanese yen)

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