* Trading remains choppy before ECB * Unicharm hits record high on strong profit report By Ayai Tomisawa TOKYO, Jan 22 (Reuters) – Japanese shares were flat in choppy trade as the market digested expectations the European Central Bank will unveil new stimulus measures at its meeting later on Thursday, while a pause in the weak yen kept investors sidelined.

The Nikkei 225 share average was flat at 17,273.54 in mid-morning trade, while the broader Topix fell 0.3 percent to 1,386.99.

Analysts said that hopes that the ECB will launch a large-scale sovereign bond-buying programme later in the day are factored into the current market, and with Greece’s national election scheduled on the weekend, investors may refrain from taking large positions for now.

Greece faces an early national election after its parliament rejected Prime Minister Antonis Samaras’ nominee for president on Dec. 29.

A source told Reuters the ECB’s Executive Board had proposed a programme that would enable the bank to buy 50 billion euros ($ 58 billion) in bonds per month starting in March. ECB President Mario Draghi will speak to the media at 1330 GMT on Thursday.

“If the ECB eases policy as expected, the news may be priced in quickly and investors may take profits,” said Hikaru Sato, a senior technical analyst at Daiwa Securities. “If the ECB’s decision fails to meet market expectations, then there will likely be confusion in the market and shares will be sold, so either way, investors are staying on the sidelines.” Exporters were mixed, with Toyota Motor Corp falling 0.5 percent, Honda Motor Co rising 0.2 percent and Panasonic Corp dropping 0.8 percent.

Against the yen, the dollar was back at 117.89, having reversed all of Tuesday’s gains.

Bucking the trend, Unicharm Corp rose as high as 3.7 percent to a record 3,192 yen after the Nikkei business daily reported that the company’s Apr-Dec operating profit likely reached 59 billion yen, compared to a previously forecast 56.6 billion yen due to strong sales of high-end diapers in the domestic market and brisk sales in overseas markets.

The new JPX-Nikkei Index 400 dropped 0.5 percent to 12,582.27.

(Editing by Jacqueline Wong)