By Lisa Baertlein

Starbucks Corp on Tuesday said it plans to buy the remaining 60.5 percent share of Starbucks Coffee Japan Ltd that it does not already own in a two-step deal valued at about $913.5 million.

Starbucks Japan has operated as a joint venture between Starbucks and its partner Sazaby League since 1995. Over the summer, Sazaby approached the world's biggest coffee chain about selling its ownership stake in Starbucks Japan, Starbucks said in a statement.

There are roughly 1,050 Starbucks cafes in Japan, which Starbucks said will be its second-largest market in terms of revenue from its coffee shops.

Despite Japan's economic difficulties, those shops have profit margins that are among the highest in the world, Starbucks executives said on a conference call with analysts.

Starbucks also has opportunities to add more shops, expand product sales through grocery and food service channels and to boost the company's relatively small share of canned coffee and other ready-to-drink products that are popular in Japan, they added.

Sazaby will begin tendering shares beginning on Sep. 26. The purchase price for Sazaby's 39.5 percent stake is 965 yen per share, for a total of 55 billion yen (about $505 million). When that transaction is completed, Starbucks will have a controlling 79 percent interest in Starbucks Japan.

Shortly afterward, Starbucks will begin to buy the remaining 21 percent ownership interest held by public shareholders and option holders of Starbucks Japan's common stock for a purchase price of 1,465 yen per share, for a total of 44.5 billion yen (about $408.5 million).

The public price per share of 1,465 yen represents a premium of 11.6 percent to the 30-day average price of Starbucks Japan's stock, a 4.7 percent premium to the closing price on Sept. 22, and a 51.8 percent premium to the price Starbucks is paying Sazaby for its shares, the company said.

All steps in the tender offer process have been unanimously approved by the boards of directors of Starbucks, Sazaby and Starbucks Japan, and the transactions are expected to be fully completed during the first half of calendar 2015, Starbucks said.

Starbucks expects the deal to be immediately accretive to earnings, excluding items.

Shares in Starbucks were virtually unchanged at $73.96 in extended trading.